NOAA's National Centers for Environmental Information
Issued 13 August 2024
Please note that the values presented in this report are based on preliminary data. They will change when the final data are processed, but will not be replaced on these pages.
National Drought Highlights
- Based on the Palmer Drought Index, severe to extreme drought affected about 6% of the contiguous United States as of the end of July 2024, about the same as last month. About 7% of the contiguous U.S. fell in the severely to extremely wet categories.
- About 20% of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of July.
- On a broad scale, the 1980s and 1990s were characterized by unusual wetness with short periods of extensive droughts, the 1930s and 1950s were characterized by prolonged periods of extensive droughts with little wetness, and the first two decades of the 2000s saw extensive drought and extensive wetness (moderate to extreme drought graphic, severe to extreme drought graphic).
- A file containing the national monthly percent area severely dry and wet from 1900 to present is available for the severe to extreme and moderate to extreme categories.
- Historical temperature, precipitation, and Palmer drought data from 1895 to present for climate divisions, states, and regions in the contiguous U.S. are available at the Climate Division: Temperature-Precipitation-Drought Data page. These filenames begin with "climdiv".
U.S. Drought Monitor information is currently unavailable.
Detailed Drought Overview
The upper-level atmospheric circulation over North America during July 2024 was characterized by high pressure ridging across the southern CONUS with the jet stream keeping the main storm track across the northern states and southern Canada. Short-wave troughs and ridges migrated through the jet-stream flow. Frequently during the month, these troughs favored a region stretching from the Great Lakes to Lower Mississippi Valley, while ridges tended to dominate the East Coast and much of the West. This pattern resulted in near- to cooler-than-normal monthly temperatures from the Great Lakes to central and southern Plains, with warmer-than-normal temperatures along the East Coast and across much of the West.
Surface low-pressure systems and cold fronts followed the troughs. They triggered areas of rain across the Great Plains and Midwest during the first week of the month. On July 8-12, the remnants of Hurricane Beryl tracked across eastern Texas then merged with a cold front and moved to the Great Lakes and St. Lawrence Seaway, dropping heavy rain along its path. High pressure generated unusually hot and dry weather over the Southeast the week after Beryl, but then an upper-level trough brought a cold front which stalled out over the Southeast. Fed by abundant Gulf of Mexico and Atlantic moisture, showers and thunderstorms formed along the front day after day to bring above-normal rain to the region during the last half of the month (precipitation anomaly maps for July 18-24 and 24-30). Meanwhile, even though occasional troughs and cold fronts brushed the western CONUS, bringing rain to some areas, the dominant ridging gave most of the West a dry and hot July. Troughing brought wetter- and near to cooler-than-normal weather to much of Alaska. Ridging and strong trade winds kept Hawaii drier than normal for the month.
The hot and dry pattern in the West for much of the month, and dry hot weather in the Southeast for part of the month, contributed to dozens of large wildfires. Abnormally hot and dry weather over Canada contributed to numerous large wildfires over that country as well (wildfire maps for July 5, 15, 25, 31) (map legend). Groundwater was low and soils dry across large parts of western Canada and the central and western CONUS as well as the central Appalachians (GRACE surface and root zone soil moisture; SPoRT soil moisture for 0-10 cm, 0-40 cm, 0-100 cm, 0-200 cm depths; CPC soil moisture model). The dryness in the central Appalachians resulted in record to near-record low monthly streamflow values.
The dry conditions resulted in expansion or intensification of drought and abnormal dryness across much of the West and central Appalachians and parts of the central and southern Plains and New England. Drought and abnormal dryness also expanded in much of Hawaii. But the above-normal precipitation in the Southeast, Midwest, and parts of the southern Plains and Southwest contracted or reduced the intensity of drought and abnormal dryness compared to the end of June. Drought expansion exceeded contraction with the USDM-based national moderate-to-exceptional drought footprint across the CONUS increasing from 18.7% at the end of June to 19.9% at the end of July (from 15.8% to 16.9% for the 50 states and Puerto Rico).
According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 19.5% of the CONUS was in moderate to extreme drought at the end of July, which is almost double the value at the end of June.
Drought conditions at the end of July, as depicted on the July 30, 2024 USDM map, included the following core drought and abnormally dry areas:
- In the West, moderate (D1) to exceptional (D4) drought covers about 47.0% of the Pacific Northwest, which is about twice as much as last month, and moderate to extreme (D3) drought affected about 22.0% of the Southwest (Four Corners states), which is about the same as last month. For the West as a whole, the percent area experiencing moderate to exceptional drought, according to USDM statistics, increased from 18.8% at the end of June to 28.7% at the end of July. Based on the Palmer Drought Index, the drought area across the West as a whole jumped from 8.6% at the end of June to 25.3% at the end of July. Reservoir levels ranged from below to above average, with low reservoir levels most common in the Southwest and Pacific Northwest basins.
- New Mexico set a new drought duration record at the end of July. According to USDM statistics, New Mexico has experienced moderate or worse drought for 354 weeks, beginning on October 24, 2017.
- In the Great Plains, moderate to severe drought covered about 22.0% of the central to northern Plains, which is more than last month, and 23.8% of the southern Plains, which is less than last month. The Lower Mississippi River Valley experienced a slight decrease in the drought area , going from 3.3% at the end of June to 2.7% at the end of July. Drought expanded a bit in Tennessee this month, covering 28.0% of the state by the end of July. Taken together, the southern Plains, Lower Mississippi Valley, and Tennessee (South region) saw moderate to extreme drought shrink from 19.7% at the end of June to 16.1% at the end of July.
- Oklahoma set a new drought duration record at the end of July. According to USDM statistics, Oklahoma has experienced moderate or worse drought for 262 weeks, beginning on July 30, 2019.
- In the Midwest, moderate to severe (D2) drought covered eastern portions of the Ohio Valley, with the Midwest drought area decreasing slightly from 5.6% at the end of June to 4.5% at the end of July.
- Drought significantly contracted in the Southeast this month, shrinking from 53.3% at the end of June to 20.8% at the end of July. Areas of extreme drought persisted in parts of Virginia and South Carolina.
- Drought expanded in the Northeast this month, growing from 12.2% of the region at the end of June to 20.8% by the end of July. Extreme drought developed in southern parts of the region.
- Moderate to severe drought significantly expanded in Hawaii, growing from 8.9% of the state at the end of June to 54.7% by the end of July.
- A small area of moderate drought persisted in Alaska, covering about 1.1% of the state at the end of July.
- In the U.S.-Affiliated Pacific Islands (USAPI), only 1 station was abnormally dry at the end of July. This compares to 3 abnormally dry, 1 with moderate drought, and 2 with severe drought at the end of June.
Palmer Drought Index
The Palmer drought indices measure the balance between moisture demand (evapotranspiration driven by temperature) and moisture supply (precipitation). The Palmer Z Index depicts moisture conditions for the current month, while the Palmer Hydrological Drought Index (PHDI) and Palmer Drought Severity Index (PDSI) depict the current month's cumulative moisture conditions integrated over the last several months.
While both the PDSI and PHDI indices show long-term moisture conditions, the PDSI depicts meteorological drought while the PHDI depicts hydrological drought. The PDSI map may show less severe and extensive drought (as well as wet spell conditions) in some parts of the country than the PHDI map because the meteorological conditions that produce drought and wet spell conditions are not as long-lasting as the hydrological impacts.
Used together, the Palmer Z Index and PHDI maps show that short-term drought occurred across much of the West and parts of the northern Plains and Upper Mississippi Valley, expanding long-term drought areas and shrinking long-term wet areas; in the central Appalachians to western Ohio Valley, expanding areas of long-term drought; and in much of the Florida peninsula, introducing long-term drought (PHDI maps for July compared to June). Short-term wet conditions occurred in the western Gulf of Mexico Coast to the Great Lakes, in northern New England, and in the Carolinas, expanding or intensifying long-term wet conditions or ending long-term drought.
Standardized Precipitation Index
The Standardized Precipitation Index (SPI) measures moisture supply. The SPI maps here show the spatial extent of anomalously wet and dry areas at time scales ranging from 1 month to 24 months.
The SPI maps illustrate how moisture conditions have varied considerably through time and space over the last two years. Severely dry conditions persisted across the western Ohio Valley and central Appalachians to the Mid-Atlantic coast at 1- to 3-month time scales, with parts of this area dry at 6 to 24 months. Parts of the Florida peninsula had dryness at 1, 3, and 6 months. Much of the West and adjacent parts of the Plains were dry at 1 to 3 months, with parts of the northern half of the West dry at 6 to 24 months. Parts of the Rio Grande Valley were dry at all time scales. Parts of the central Plains had dryness at 6 and 12-24 months. Wet conditions dominate much of the Midwest at all time scales, eastern parts of the northern Plains at 3 to 24 months, parts of the Southwest at 2 to 3 months, parts of the West at 6 to 24 months, much of the Gulf of Mexico Coast at 1 to 9 months, parts of the Northeast at 1 to 6 months and most of this region at 9 to 24 months, and parts of the Southeast at 1 and 3 to 24 months.
Standardized Precipitation Evapotranspiration Index
The SPI measures water supply (precipitation), while the SPEI (Standardized Precipitation Evapotranspiration Index) measures the combination of water supply (precipitation) and water demand (evapotranspiration as computed from temperature). Warmer temperatures tend to increase evapotranspiration, which generally makes droughts more intense.
For the Northern Hemisphere, July marks the middle of climatological summer, which is the season when sun angle, temperatures, and evapotranspiration are maximum. During July 2024, temperatures were warmer than normal across much of the West and from the eastern Gulf of Mexico Coast to New England, with record warmth along the West Coast and in parts of the East Coast. Evapotranspiration rates were unusually high, and where it was both hot and dry, the evapotranspiration exacerbated the drought conditions, especially in the central Appalachians and along the West Coast. The 1-month SPEI values were more extreme (dry) than the corresponding SPI across the West and in central Appalachia. Temperatures were unusually warm across much of the CONUS for the last 2 to 3 months. Dryness in the West and central Appalachia extended back over this time frame. The heat made drought conditions worse, so the SPEI values were more extreme than the SPI values for the last 2 to 3 months. Conditions were not as dry at the 6- to 12-month time scales, so the SPEI values were not as extreme, but they were still drier than the corresponding SPI values due to the persistent widespread anomalous heat (SPEI maps for the last 1, 2, 3, 6, 9, 12 months) (SPI maps for the last 1, 2, 3, 6, 9, 12 months).
The combination of heat and dryness in the West resulted in record to near-record low SPEI values:
- California had a record dry 1-month July SPEI while the SPI was barely on the dry side of normal. The hottest July on record contributed to the record-dry SPEI.
- California also had the driest 2-month July SPEI while the SPI was dry but not even in the top ten category.
- Oregon had the second driest 1-month July SPEI statewide while the SPI was dry but not in the top ten. The state had the second hottest July on record.
- Nevada had the second driest 2-month July SPEI statewide while the SPI was dry but not in the top ten.
The last 1 to 6 years have been unusually warm across most of the CONUS (state temperature rank maps for the last 1, 2, 3, 4, 5 years). Precipitation in the last 12 months has helped reduce deficits in many areas. But July 2024 was very dry in the central Appalachians and dry across most of the West and northern Plains, the last 2 years have been extremely dry in the Pacific Northwest, the last 3 years were dry in the central and southern Plains, and the last 4 to 5 years have been quite dry in the West to Great Plains (state precipitation rank maps for the last 1, 2, 3, 4, 5 years). In the last 1 to 6 years, the SPEI is more extreme than the SPI in the Pacific Northwest but especially in the Southwest to Lower Mississippi Valley. In the western U.S., where drought has dominated for much of the last 20 years, the combination of excessive heat and dryness has resulted in more extreme SPEI values than SPI values in parts of the West for the last 2 to 6 years, especially at the longer time scales (SPEI maps for last 12, 18, 24, 30, 36, 48, 60, 72 months) (SPI maps for last 12, 18, 24, 30, 36, 48, 60, 72 months).
Regional Discussion
Rio Grande River Basin
During October 2023-July 2024, parts of the Rio Grande River Basin were wetter than normal, parts drier than normal, and parts near normal. But very dry and hot conditions of summer and early fall last year created significant precipitation deficits and expanded drought. July 2024 was near to drier than normal, but April and May 2024 were mostly drier than normal. The basin had the 47th wettest July in the 1895-2024 record, but 50th driest August-July (last 12 months). Temperatures have also been anomalously warm — July ranked 19th warmest in the 130-year record, while August-July was the warmest such 12-month period. According to the USDM, 60.1% of the basin was in moderate to exceptional drought at the end of July, which is less than the 67.0% at the end of June. Based on the Palmer Drought Index, 66.7% of the basin was in moderate to extreme drought at the end of July, which is the same as the end of June but less than the peak of 100% that occurred just last year and many times in the last 30 years, 1950s, and early 1900s.
Hawaii
July 2024 was drier than normal across all of the main Hawaiian Islands. Oahu and Kauai were wetter than normal at the 4-month time scale while the eastern islands were drier than normal. Drier-than-normal conditions dominated at longer time scales except on Oahu (precipitation anomaly maps for the last 1, 3, 4, 6, 7, 9, 10, 12 months) (climate engine model percent of normal precipitation map for the last month).
Monthly streamflow was near to below normal across most of the main islands. Based on satellite analyses (stressed vegetation, drought stress, VHI), vegetation was stressed on parts of the Big Island, Molokai, and Maui.
Severe drought continued on the Big Island and Maui, with abnormal dryness and moderate drought on the other main islands. The drought area in Hawaii grew dramatically from 8.9% at the end of June to about 54.7% of the state on the July 30, 2024 USDM map.
Alaska
July 2024 was drier than normal in some southern and eastern areas of Alaska, but wetter than normal in most other areas. The southern Panhandle was persistently dry at 1- to 6-month time scales, there were drier-than-normal stations in the Cook Inlet/Northwest Gulf region at 1 to 12 months, and the Aleutians were mostly drier than normal at 4 and 10-12 months. The Southeast Interior was mostly drier than normal in July, while several stations in the east-central interior area were drier than normal at 1-10 months (low elevation station precipitation anomaly maps for the last 1, 3, 4, 6, 7, 9, 10, 12 months) (high elevation SNOTEL station precipitation percentile maps for the last 1, 3, and 12 months) (SNOTEL basin and station percent of normal precipitation maps for the last 1, 3, and 12 months) (climate division precipitation rank maps for the last 1, 3, 6, 7, and 12 months) (climate engine model percent of normal precipitation map for the last month) (Leaky Bucket model precipitation percentile map).
July temperatures averaged near to cooler than normal across most of the state, with some warmer-than-normal stations in the panhandle and east-central areas. Warmer-than-average temperatures were more widespread at the 3-month time scale with cooler-than-normal stations dominating the western two-thirds of Alaska. At the 6- to 12-month time scales, temperatures were warmer than average across the state when compared to the long-term (1925-2024) average. When compared to more recent (1991-2020) normals, cooler-than-normal temperatures were still evident in southwestern parts of the state because of a pronounced warming trend in recent decades (low elevation station temperature anomaly maps for the last 1, 3, 7, 10, 12 months) (climate division temperature rank maps for the last 1, 3, 6, 7, and 12 months) (gridded temperature percentile maps for the last 1, 3, and 7 months) (Leaky Bucket model temperature percentile map).
Monthly streamflow was below normal for some streams in the east, Northwest Gulf, and South Panhandle, but most streams were near to above normal. Satellite observations of vegetative health (stressed vegetation, drought stress, VHI) revealed some areas of stressed vegetation. Satellite-based or modeled observations of groundwater and soil moisture (GRACE root zone and GRACE surface soil moisture; SPoRT estimates of soil moisture at four depths [0-10 cm, 10-40 cm, 40-100 cm, 100-200 cm]; SMOS soil moisture; Leaky Bucket modeled soil moisture) suggested some dryness was occurring in parts of the south and east.
Areas of abnormal dryness continued in the east with moderate drought continuing in the southern Panhandle, covering about 1.1% of the state on the July 30, 2024 USDM map, which was slightly less than last month.
Puerto Rico and U.S. Virgin Islands
July 2024 was mostly drier than normal across the U.S. Virgin Islands (USVI) and Puerto Rico (PR). Wetter-than-normal conditions dominated the 4- to 12-month time periods with some drier-than-normal areas in PR at 7 to 12 months (low elevation station precipitation anomaly maps for the last 1, 3, 4, 6, 7, 9, 10, 12 months) (climate engine model percent of normal precipitation map for the last month: PR and USVI, Caribbean and Gulf of Mexico region).
Root zone analysis indicated that soil conditions were dry across the northwestern and southern coasts and some central to northeast areas of PR, with dryness more evident in the mid-level soil layers compared to shallower and deeper soil layers (root zone soil saturation fraction, SPoRT estimates of soil moisture at four depths [0-10 cm, 10-40 cm, 40-100 cm, 100-200 cm]). Satellite observations of vegetative health (stressed vegetation for PR and USVI, drought stress for PR and USVI, VHI for PR and USVI) revealed few if any areas of stressed vegetation. Monthly streamflow on PR showed near- to above-normal stream levels. In the USVI, groundwater levels declined during July at St. John, St. Thomas, and St. Croix. The end-of-July groundwater level was in the middle third of the recent historical record at St. Croix, but continued in the upper third at St. John and St. Thomas.
PR and the USVI continued free of drought and abnormal dryness on the July 30, 2024 USDM map.
CONUS State Precipitation Ranks
July 2024 was drier than normal across much of the western and central CONUS as well as the western Ohio Valley and central Appalachia to parts of the Mid-Atlantic Coast, with record dryness occurring locally in the West. Fourteen states had a precipitation rank in the driest third of the historical record for July. One ranked in the top ten driest category — West Virginia (eighth driest July on record) — and one came close: Utah (15th driest).
May-July 2024 was drier than normal across essentially the same areas as July, except a little more of the Ohio Valley and a little less of the Plains. Twelve states had a precipitation rank in the driest third of the historical record for May-July. One ranked in the top ten driest category — Nevada (eighth driest) — and two came close: Utah (14th driest) and West Virginia (14th driest).
Parts of the CONUS have had very dry conditions at various times during the past 6 to 12 months, but the location of the dryness varied and some of the dry areas had wetter-than-normal conditions during intermittent months (low elevation station precipitation anomaly maps for the last 6,7, 9, 10, and 12 months) (climate division precipitation rank maps for the last 6, 7, and 12 months) (gridded precipitation percentile maps for the last 7 months). Persistently dry areas include parts of the Plains (especially the Rio Grande Valley), Pacific Northwest, Great Basin, Ohio Valley to central Appalachians, and Lower Mississippi to Tennessee Valley. Those states that were dry experienced enough precipitation over other parts of the state to balance out the dryness. So, only three states ranked in the driest third of the 1895-2024 record for February-July, two for January-July, and three for August-July; no state ranked in the top 10 driest category for these three time periods.
Agricultural Belts
During July 2024, the Primary Corn and Soybean agricultural belt was mostly cooler than normal with a mixed precipitation anomaly pattern. The month ranked as the 20th wettest and 43rd coolest July, regionwide, in the 1895-2024 record.
March marks the beginning of the growing season for the Primary Corn and Soybean belt. March-July 2024 was warmer than normal and mostly wetter than normal in the northwest to drier than normal in the southeast. The period ranked as the eighth warmest and ninth wettest March-July, regionwide, in the historical record.
According to the U.S. Department of Agriculture (USDA), as of July 30, 2024, drought affected approximately 32% of barley production, 5% of corn production, 11% of cotton production, 29% of sorghum production, 5% of soybean production, 16% of spring wheat production, 32% of winter wheat production, 20% of hay acreage, 15% of the cattle inventory, 10% of the milk cow inventory, and 20% of the sheep inventory.
Based on July 28 USDA statistics, 9% of the corn crop, 8% of the soybean crop, 4% of the spring wheat crop, and 29% of the pasture and rangeland were in poor to very poor condition, and 32% of the nation's topsoil and 31% of the subsoil were short or very short of moisture (dry or very dry). States with the driest soils were in the Mid-Atlantic to Ohio Valley, Pacific Northwest, and central and southern Plains to Rocky Mountains, followed by states in New England and the Southeast.
U.S.-Affiliated Pacific Islands
The NOAA National Weather Service (NWS) offices, the Pacific ENSO Applications Climate Center (PEAC), and partners provided reports on conditions across the Pacific Islands.
In the U.S. Affiliated Pacific Islands (USAPI) (maps — Federated States of Micronesia [FSM], Northern Mariana Islands, Marshall Islands [RMI], Republic of Palau [ROP], American Samoa, basinwide), July 2024 was drier than normal in the Marianas, American Samoa, and parts of the Marshalls and FSM, but near to wetter than normal in the Republic of Palau and other parts of the FSM and Marshalls.
Monthly precipitation amounts were below the monthly minimum needed to meet most water needs (4 inches in the Marianas and Pago Pago, and 8 inches elsewhere) in the northern Marianas (Saipan) and parts of the Marshall Islands. July precipitation was above the monthly minimums in American Samoa, Palau, the FSM, and most of the Marianas and Marshalls. The 4- and 8-inch thresholds are important because, if monthly precipitation falls below the threshold, then water shortages or drought become a concern.
The tropical Pacific climatology can experience extremes in precipitation, from very low precipitation during the dry season to very high precipitation during the wet season. This can result in monthly normal precipitation values that are different from the monthly minimum needed to meet most water needs, and this can lead to percent of normal values that seem odd. This was the case during July 2024, which is in the wet season for Palau, the Marianas, and most of the FSM and Marshalls, and in the dry season for American Samoa. Precipitation was above the monthly minimum but below normal (1981-2010 normal), because the normals are high, at:
- Guam: July 2024 precipitation 7.51 inches, July normal mean 12.14 inches, July normal median 10.14 inches.
- Rota: July 2024 precipitation 6.61 inches, July normal mean 9.86 inches.
- Kapingamarangi: July 2024 precipitation 9.21 inches, July normal mean 13.16 inches, July normal median 14.15 inches.
- Lukunor: July 2024 precipitation 9.21 inches, July normal mean 16.46 inches, July normal median 15.93 inches.
- Majuro: July 2024 precipitation 8.85 inches, July normal mean 11.93 inches, July normal median 11.17 inches.
- Pago Pago: July 2024 precipitation 4.50 inches, July normal mean 6.47 inches, July normal median 5.55 inches.
- Wotje: July 2024 precipitation 4.52 inches, July normal mean 4.31 inches.
In the table below, the station identified as Koror is Palau International Airport (Airai).
| Station Name | Aug 2023 | Sep 2023 | Oct 2023 | Nov 2023 | Dec 2023 | Jan 2024 | Feb 2024 | Mar 2024 | Apr 2024 | May 2024 | Jun 2024 | Jul 2024 | Aug- Jul |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 118% | 112% | 110% | 141% | 100% | 100% | 76% | 40% | 99% | 95% | 132% | 128% | 102% |
| Guam NAS | 132% | 98% | 152% | 84% | 107% | 59% | 62% | 78% | 283% | 112% | 129% | 74% | 94% |
| Kapingamarangi | 121% | 256% | 117% | 153% | 74% | 188% | 206% | 196% | 99% | 95% | 48% | 65% | 114% |
| Koror | 125% | 130% | 108% | 85% | 67% | 136% | 140% | 48% | 184% | 59% | 98% | 106% | 97% |
| Kosrae | 104% | 123% | 153% | 163% | 44% | 90% | 119% | 96% | 84% | 124% | 109% | 154% | 94% |
| Kwajalein | 81% | 61% | 103% | 156% | 111% | 53% | 52% | 196% | 80% | 166% | 147% | 111% | 105% |
| Lukonor | 74% | 115% | 136% | 81% | 94% | 64% | 76% | 153% | 164% | 150% | 113% | 58% | 93% |
| Majuro | 95% | 56% | 86% | 101% | 70% | 57% | 74% | 16% | 111% | 150% | 99% | 79% | 84% |
| Pago Pago | 42% | 156% | 91% | 36% | 195% | 142% | 201% | 71% | 115% | 211% | 186% | 81% | 116% |
| Pohnpei | 219% | 156% | 83% | 178% | 48% | 50% | 170% | 91% | 116% | 121% | 104% | 137% | 118% |
| Saipan | 142% | 109% | 92% | 133% | 158% | 74% | 79% | 83% | 67% | 53% | 213% | 42% | 104% |
| Yap | 145% | 70% | 88% | 79% | 41% | 90% | 55% | 14% | 33% | 77% | 55% | 134% | 80% |
| Station Name | Aug 2023 | Sep 2023 | Oct 2023 | Nov 2023 | Dec 2023 | Jan 2024 | Feb 2024 | Mar 2024 | Apr 2024 | May 2024 | Jun 2024 | Jul 2024 | Aug- Jul |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 15.23" | 13.07" | 12.70" | 14.93" | 11.22" | 10.05" | 5.49" | 3.30" | 12.38" | 10.76" | 15.38" | 15.37" | 139.88" |
| Guam NAS | 19.47" | 12.46" | 17.40" | 6.18" | 5.49" | 2.38" | 1.88" | 1.62" | 7.17" | 3.82" | 8.00" | 7.51" | 93.38" |
| Kapingamarangi | 9.87" | 25.45" | 9.55" | 14.14" | 7.33" | 17.18" | 19.05" | 22.43" | 13.53" | 11.42" | 6.59" | 9.21" | 165.75" |
| Koror | 16.86" | 15.26" | 12.80" | 9.65" | 7.46" | 13.85" | 11.97" | 3.56" | 13.44" | 7.01" | 17.05" | 19.72" | 148.63" |
| Kosrae | 14.72" | 17.52" | 16.79" | 22.60" | 7.06" | 15.04" | 15.43" | 15.34" | 14.64" | 21.96" | 16.03" | 22.99" | 200.12" |
| Kwajalein | 7.86" | 6.60" | 11.46" | 17.65" | 7.42" | 1.66" | 1.37" | 4.61" | 4.19" | 11.17" | 10.17" | 10.98" | 95.14" |
| Lukonor | 10.33" | 11.63" | 15.43" | 7.40" | 10.54" | 5.42" | 6.83" | 14.20" | 18.58" | 17.54" | 13.12" | 9.21" | 140.23" |
| Majuro | 11.07" | 6.27" | 10.98" | 13.51" | 7.96" | 4.38" | 5.11" | 1.08" | 10.43" | 15.17" | 10.92" | 8.85" | 105.73" |
| Pago Pago | 2.26" | 10.18" | 8.45" | 3.69" | 25.00" | 18.99" | 24.09" | 7.61" | 10.83" | 20.37" | 9.91" | 4.50" | 145.88" |
| Pohnpei | 31.21" | 19.57" | 12.71" | 26.39" | 7.76" | 6.65" | 16.27" | 12.02" | 21.36" | 24.07" | 15.34" | 21.09" | 214.44" |
| Saipan | 18.62" | 11.03" | 9.80" | 7.44" | 6.07" | 1.87" | 2.05" | 1.57" | 1.76" | 1.26" | 7.71" | 3.74" | 72.92" |
| Yap | 21.43" | 9.46" | 10.74" | 6.95" | 3.53" | 5.73" | 2.84" | 0.64" | 1.83" | 6.03" | 6.61" | 20.23" | 96.02" |
| Station Name | Aug 2023 | Sep 2023 | Oct 2023 | Nov 2023 | Dec 2023 | Jan 2024 | Feb 2024 | Mar 2024 | Apr 2024 | May 2024 | Jun 2024 | Jul 2024 | Aug- Jul |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 12.86" | 11.71" | 11.51" | 10.61" | 11.25" | 10.10" | 7.25" | 8.32" | 12.47" | 11.30" | 11.66" | 11.98" | 136.77" |
| Guam NAS | 14.74" | 12.66" | 11.44" | 7.38" | 5.11" | 4.01" | 3.03" | 2.07" | 2.53" | 3.40" | 6.18" | 10.14" | 99.09" |
| Kapingamarangi | 8.13" | 9.93" | 8.19" | 9.27" | 9.84" | 9.15" | 9.27" | 11.43" | 13.64" | 12.08" | 13.78" | 14.15" | 145.85" |
| Koror | 13.50" | 11.77" | 11.84" | 11.39" | 11.16" | 10.18" | 8.56" | 7.44" | 7.32" | 11.83" | 17.48" | 18.53" | 152.90" |
| Kosrae | 14.22" | 14.22" | 10.94" | 13.83" | 16.11" | 16.67" | 12.93" | 16.06" | 17.51" | 17.75" | 14.64" | 14.91" | 213.87" |
| Kwajalein | 9.74" | 10.74" | 11.18" | 11.28" | 6.66" | 3.16" | 2.64" | 2.35" | 5.26" | 6.72" | 6.93" | 9.87" | 90.41" |
| Lukonor | 14.04" | 10.15" | 11.32" | 9.08" | 11.27" | 8.41" | 8.93" | 9.26" | 11.31" | 11.69" | 11.65" | 15.93" | 151.36" |
| Majuro | 11.69" | 11.17" | 12.73" | 13.44" | 11.39" | 7.74" | 6.88" | 6.58" | 9.42" | 10.11" | 11.01" | 11.17" | 125.25" |
| Pago Pago | 5.38" | 6.53" | 9.26" | 10.14" | 12.84" | 13.34" | 12.00" | 10.68" | 9.39" | 9.66" | 5.33" | 5.55" | 125.57" |
| Pohnpei | 14.26" | 12.55" | 15.27" | 14.83" | 16.08" | 13.18" | 9.55" | 13.17" | 18.41" | 19.96" | 14.81" | 15.43" | 182.36" |
| Saipan | 13.13" | 10.09" | 10.62" | 5.61" | 3.85" | 2.53" | 2.59" | 1.89" | 2.63" | 2.38" | 3.62" | 8.91" | 70.25" |
| Yap | 14.82" | 13.50" | 12.18" | 8.83" | 8.51" | 6.39" | 5.19" | 4.56" | 5.63" | 7.85" | 12.04" | 15.08" | 120.31" |
As measured by percent of normal precipitation, Guam was drier than normal at all time scales in the short term (July and the last 3 months [May-July]) and long term (year to date [January-July] and last 12 months [August 2023-July 2024]). Airai and Yap were near to wetter than normal for July but drier than normal for the other 3 time periods. Lukunor was near to wetter than normal for the year to date but drier than normal for the other 3 time periods. Majuro was wetter than normal at the 3-month time scale but drier than normal for the other 3 time periods. Saipan was near to wetter than normal at the 12-month time scale but drier than normal at the other 3 time periods. Kapingamarangi was drier than normal in the short term but wetter than normal in the long term. Kosrae was near to drier than normal in the long term but wetter than normal in the short term. Chuuk was near to drier than normal for the year to date but near to wetter than normal for the other 3 time periods. Pago Pago was drier than normal for July but wetter than normal for the other 3 time periods. Kwajalein and Pohnpei were near to wetter than normal for all 4 time periods.
Based on percent of normal average (instead of normal median values), in the Marianas Islands, July and the last 3 to 12 months were generally drier than normal across the main islands (percent of normal precipitation maps for the last 1, 3, 4, 6, 7, 9, 10, 12 months).
Based on percent of normal average (instead of normal median values), the Marshall Islands were mostly drier than normal in July and the last 3 to 12 months (percent of normal precipitation maps for the last 1, 3, 4, 6, 7, 9, 10, 12 months).
According to the July 31 USDM produced for the USAPI:
- In the Marianas, abnormal dryness ended at Guam and Rota but continued on Saipan;
- In the FSM, drought and abnormal dryness ended at Ulithi and Yap, making all of the FSM free of drought or abnormal dryness, with two stations having insufficient data for an analysis;
- In the Marshalls, four islands were free of drought and abnormal dryness, two (Mili and Utirik) had insufficient data for an analysis, and the data at Wotje was questionable so no analysis was made there for the end of the month (July 31); and
- Palau and American Samoa were free of drought an abnormal dryness.
The level of the reservoir on Majuro began the month at 31.96 million gallons, fluctuated up and down to a minimum of 30.2 million gallons on July 12 and a peak of 33.8 million gallons on the 21st, then ended the month at 31.84 million gallons. If the reservoir dips below 28.8 million gallons, drought becomes a concern. Satellite observations of vegetative health (drought stress, stressed vegetation, VHI) revealed a few areas of stressed vegetation remaining on Guam.
The National Weather Service (NWS) office in Guam issued two Drought Information Statements (DGT) for drought for July (on July 5 and 19) and one in early August. Drought impacts included:
- water levels were still low at the beginning of July in Yap State and the northern Marshalls, but improved as beneficial rain fell throughout the month with no impacts reported by early August;
- agricultural conditions improved throughout the month with vegetation becoming greener.
July 2024 precipitation ranks ranged from dry to wet with some mid-range, based on data available at the time of this report. Some locations have had dry conditions for several months:
- Saipan: third driest July (in a 44-year record).
- Lukunor: sixth driest July (40 years).
- Jaluit: seventh driest July (41 years), sixth driest December-July and August-July.
- Kapingamarangi: 11th driest July (35 years), sixth driest April-July and seventh driest June-July and May-July, but third wettest September-July and August-July.
- Ulithi: 23rd driest (18th wettest) July (40 years), but seventh driest November-July.
- Yap: seventh wettest July (74 years), but sixth driest December-July and November-July and fifth driest September-July.
- Majuro: 13th driest July (71 years) and tenth driest September-July.
At the wet end of the scale:
- Pago Pago had the second wettest December-July (58 years).
- Kapingamarangi had the third wettest September-July and August-July (23 years).
The following analysis of historical data for the USAPI stations in the Global Historical Climatology Network-Daily (GHCN-D) dataset, augmented with fill-in data from the 1981-2010 Normals, helps put the current data into historical perspective by computing ranks based on the period of record. The table below lists the precipitation ranks for July 2024, February-July 2024 (last 6 months), and August 2023-July 2024 (the last 12 months). Some stations have a long period of record and their dataset is fairly complete, while other stations have a shorter period of record and the dataset has some missing data.
| Station | July 2024 | Feb-Jul 2024 | Aug 2023-Jul 2024 | Period of Record | |||
|---|---|---|---|---|---|---|---|
| Rank | Years | Rank | Years | Rank | Years | ||
| Ailinglaplap | 37 | 40 | 30 | 40 | 25 | 37 | 1981-2024 |
| Airai | 50 | 74 | 34 | 73 | 36 | 72 | 1951-2024 |
| Chuuk | 56 | 74 | 28 | 73 | 34 | 73 | 1951-2024 |
| Fananu | -- | 8 | -- | 3 | -- | 3 | 2003-2023 |
| Guam | 16 | 68 | 30 | 67 | 27 | 67 | 1957-2024 |
| Jaluit | 7 | 41 | 8 | 40 | 6 | 38 | 1981-2024 |
| Kapingamarangi | 11 | 35 | 18 | 28 | 19 | 21 | 1962-2024 |
| Kosrae | 49 | 56 | 22 | 46 | 18 | 37 | 1954-2024 |
| Kwajalein | 50 | 73 | 38 | 72 | 30 | 72 | 1952-2024 |
| Lukunor | 6 | 40 | 29 | 40 | 14 | 27 | 1981-2024 |
| Majuro | 13 | 71 | 21 | 70 | 12 | 70 | 1954-2024 |
| Mili | -- | 38 | -- | 38 | -- | 35 | 1981-2024 |
| Nukuoro | 30 | 41 | 4 | 40 | 15 | 39 | 1981-2024 |
| Pago Pago | 21 | 59 | 53 | 58 | 48 | 58 | 1966-2024 |
| Pingelap | -- | 39 | -- | 38 | -- | 34 | 1981-2024 |
| Pohnpei | 58 | 74 | 56 | 73 | 62 | 73 | 1951-2024 |
| Saipan | 3 | 44 | 14 | 43 | 18 | 35 | 1981-2024 |
| Ulithi | 23 | 40 | 15 | 39 | 19 | 36 | 1981-2024 |
| Utirik | -- | 16 | -- | 8 | -- | 4 | 1985-2020 |
| Woleai | 26 | 43 | -- | 33 | -- | 28 | 1968-2024 |
| Wotje | 20 | 40 | 15 | 40 | 7 | 37 | 1981-2024 |
| Yap | 68 | 74 | 10 | 73 | 11 | 73 | 1951-2024 |
SPI values for seven time periods for Pacific Islands, computed by the Honolulu NWS office:
NOAA Regional Climate Centers
More information, provided by the NOAA Regional Climate Centers and others, can be found below.
Southeast
As noted by the Southeast Regional Climate Center, temperatures were above average across most of the Southeast in July. Following a mostly dry June, precipitation in July was above average across a large portion of the Southeast. Drier-than-average conditions were found across parts of the Florida Peninsula and northern Virginia. Marathon Key, FL recorded 1.04 inches (26 mm) for the month, which was only 25 percent of normal. West Palm Beach, FL and Fort Lauderdale, FL each recorded less than half of their expected monthly totals. Harrisonburg, VA (1893-2024) recorded just 0.98 inch (25 mm) for the month, making it the fourth driest July on record. Precipitation was below average across much of Puerto Rico. Monthly totals were near average on Saint Croix and above average on Saint Thomas and Saint John. San Juan, PR tied its all-time warmest minimum temperature of 83 degrees F (28.3 degrees C) on the 4th and again on the 26th.
July began with over half of the region in at least moderate (D1) drought, while another third of the region was abnormally-dry (D0). Areas of severe (D2) drought were found across parts of Virginia, the Carolinas, and Georgia. In contrast, much of South Florida and the northwest Panhandle, as well as southern Alabama, were free of any drought or abnormal dryness. By the end of the month, drought conditions had been eliminated across Florida, much of Alabama and Georgia, and eastern portions of North Carolina and Virginia, with just a few pockets of abnormal dryness (D0) remaining. Moderate (D1) drought persisted across much of the interior of the region, with small pockets of severe (D2) drought emerging across northern portions of Alabama and Georgia. Drought conditions also worsened across eastern portions of South Carolina and northern Virginia, with extreme (D3) drought emerging during the month. For the second consecutive month, the Caribbean was free of any drought or abnormal dryness.
Dryland corn was in generally poor condition due to the heat and dryness during the critical pollination stage. Because initial planting was delayed by heavy rains, much of the corn tasseled during subsequent dry conditions, which led to stunted growth and reduced ear production. Parts of Virginia reported losses of up to two-thirds of the corn crop due to the prolonged dry period that began in mid-May. Other crops, including soybeans, peanuts, sorghum, cotton, and tobacco, were also stressed due to dry soils. The lack of moisture significantly hindered their growth, leading to reduced yields. Egg production in northern Virginia dropped by as much as 30 percent due to the extreme temperatures. Summer pastures did not grow sufficiently, forcing farmers to buy feed for their cattle or sell them earlier than planned. Many farmers have only been able to make one cutting of hay this season. Fall armyworms were reported in dry hay fields in eastern parts of the Carolinas and coastal Alabama. Pumpkins planted earlier in the summer showed slow growth, indicating potential low yields this fall. Precipitation that fell later in the month improved field conditions and pastures in some areas, but also contributed to diseases like white mold and an increase in pests and insects.
South
As explained by the Southern Regional Climate Center, monthly temperatures were split across the Southern region with above-normal temperatures in the western portions of the region, below-normal temperatures in the center, and above-normal temperatures in the east of the region. July precipitation was mixed across the region with below-normal precipitation in the west, well-above-normal precipitation in the central portions, and near-normal in the East.
As of July 30th, 9.27 percent of the Southern region remained drought free, down 3.42 percent from 12.69 percent of July 2nd according to the USDM. Most of the improvement was in areas experiencing Moderate Drought. Areas experiencing Severe Drought or worse held steady in July ending with 6.85 percent of the Southern region in D2 or worse. Extreme and Exceptional drought at this time is restricted to the Big Bend area of Texas and Central Texas. Southwestern Oklahoma, northcentral Mississippi, and Tennessee are areas where Moderate Drought is persisting. Louisiana, East Texas, much of the Texas Panhandle, southeastern Oklahoma, southern Arkansas, southern Mississippi, and northern Tennessee remain drought free as of July 30th. Relatively wetter conditions and somewhat more moderate temperatures have aided the cotton crop in Texas, Oklahoma, and Louisiana with 40 percent (23 percent higher than last year), 61 percent (6 percent higher), and 82 percent (3 percent higher) reported as being in Good to Excellent condition by the USDA on July 28th. Crops in Tennessee, Mississippi, and Arkansas are off last year's pace somewhat with 53 percent (24 percent lower), 55 percent (12 percent lower), and 75 percent (3 percent lower) in Good to Excellent condition due to drier and warmer conditions in these states. Flooding in the path of Hurricane Beryl in early July was prevalent from Houston heading northwest to Tennessee, due to many areas being already saturated from rainfall earlier in the season.
Midwest
As described by the Midwest Regional Climate Center, the preliminary average July temperature for the Midwest was 72.2 degrees F (22.3 degrees C), which was 0.5 degrees F (0.3 degrees C) below the 1991-2020 normal. This breaks an 11 consecutive month stretch of above-normal monthly temperatures for the Midwest region. Preliminary July precipitation totaled 4.88 inches (124 mm) for the Midwest, which was 0.78 inch (20 mm) above normal, or 119 percent of normal. Much of Ohio missed out on the soaking rains that affected other parts of the Midwest during July. Mansfield, in north-central Ohio, had its third driest July in 105 years with just 1.24 inches (31.5 mm) of rain. Drought conditions expanded in Ohio with 40 percent of the state ending the month in drought and 32 percent abnormally dry.
Northeast
As summarized by the Northeast Regional Climate Center, July was full of extremes including all-time hottest temperatures, intensifying drought, record-setting rainfall, and a record number of tornadoes. The Northeast had its 10th-hottest July since recordkeeping began in 1895 with an average temperature of 72.3 degrees F, 2.2 degrees F above normal. July precipitation was 3.47 inches regionwide, 80 percent of normal.
The USDM from July 2 showed 12 percent of the Northeast in moderate or severe drought and 25 percent of the region as abnormally dry. Severe drought was concentrated in western Maryland and eastern West Virginia, while moderate drought extended into portions of those states, as well as Pennsylvania, Delaware, and New Jersey. Abnormal dryness was present in all states except Rhode Island. Conditions deteriorated in parts of the Mid-Atlantic during July as unusually hot temperatures, little precipitation, and enhanced evapotranspiration rates led to further reductions in soil moisture, streamflow, and, in some areas, groundwater levels. Extreme drought was introduced in eastern West Virginia and western Maryland, a first for either state since September 2010, as well as in southern Pennsylvania. The last time at least 1 percent of Pennsylvania was in extreme drought was October 2002. There was also notable expansion of severe and moderate drought in those states. Elsewhere, the variable rainfall pattern led to a mix of deterioration and improvement. For instance, a pocket of moderate drought was introduced in southeastern New Hampshire and central New Jersey but eased in Delaware and eastern Maryland. Similarly, abnormal dryness expanded in southern New Hampshire and southern Maine but eased in western New York and northern Maine.
The USDM from July 30 showed 21 percent of the Northeast in drought and 19 percent as abnormally dry. During July, some sites, particularly in parts of West Virginia, western Maryland, and southern Pennsylvania, registered record-low streamflow and/or water levels including a few along the Shenandoah River, South Branch Potomac River, Cacapon River, as well as Tygart Dam in West Virginia. Low river flows contributed to algal blooms in the Potomac River Basin. A few wells in the Mid-Atlantic also registered record-low levels. Mandatory water restrictions were enacted in parts of northeastern Massachusetts, while millions of residents in the Mid-Atlantic were asked to conserve water. A USDA report for the week ending July 14 indicated that topsoil moisture was rated adequate for only 2 percent of West Virginia (topsoil moisture was rated very short or short for the other 98 percent of the state) and only 9 percent of Maryland. USDA reports also noted that farmers were hauling water for livestock, feeding hay to cattle as pastures were not grazable, and that portions of crops like soybeans, corn, and hay, as well as some pastures and rangelands, were in very poor or poor condition. In fact, farmers in West Virginia, Maryland, and parts of Pennsylvania reported significant crop losses and stunted, drought-stressed crops such as corn, potatoes, pumpkins, and green beans. In Maryland, one grower reported losing half their sweet corn worth at least $25,000 and another grower expected to lose as much as $11,000 in wheat. Additionally, wildlife looking for food decimated crops and other plants in these three states, causing additional crop losses, resulting in the cancellations of a sunflower festival, and possibly impacting tourism at a state park. Farmers relied heavily on irrigation, in some cases increasing labor and operational costs. For instance, a grower noted an expected 10-fold increase in the farm's water bill due to significant irrigation. The effects of the drought — like stunted corn crops (for corn mazes), smaller-than-usual pumpkins, and early leaf drop — could impact fall tourism as well. Additionally, dry conditions led to an increased risk of wildfires in West Virginia and prompted burn bans to be enacted in a few central Pennsylvania communities. Smoke from wildfires burning in the western U.S. and Canada caused hazy skies in the region in late July and there were multiple instances of algal blooms and/or increased bacteria causing beaches and lakes to close throughout the month.
High Plains
As discussed by the High Plains Regional Climate Center, after staying relatively cool over the past two months, the north and northwestern parts of the High Plains were boiling hot in July. But despite the presence of a brutal heatwave, monthly temperatures were near normal. For the most part, the High Plains were dry this month and some places were below five percent of their normal precipitation. The dryness across the Front Range in Colorado finally took its toll, with numerous wildfires breaking out late in the month. Precipitation in the area has been below 50 percent for the past few months, leaving plenty of dried-up fuel for fires. Evacuations were ordered and thick clouds of smoke engulfed cities like Fort Collins. Thousands of acres were in flames at the end of the month, but the arrival of monsoonal rains could provide some relief.
In part due to the dryness and occasional heat this month, drought expanded and intensified for many. Portions of the southern High Plains experienced a two-category degradation, while over half the region is now in some form of drought category. Overall, the High Plains observed an 11 percent increase in D0 to D4 (abnormally dry to exceptional drought conditions). The dryness plaguing Wyoming led to a nine percent increase in D2 (severe drought), with most of this along the state's eastern border. Nearly the entire state is in D0 to D4, but there is some hope that upcoming rains due to the North American Monsoon could help improve the ongoing situation. Conditions in Kansas had improved this winter and into early spring; however, the state has taken a step back this month. D0 to D4 increased over 34 percent this month alone, with nearly 90 percent of the state engulfed by drought or abnormal dryness at the end of July.
West
As summarized by the Western Regional Climate Center, July was an exceptionally warm month for the West with record-setting heat at many long-term climate stations. Monthly mean temperature records were broken but several all-time daily maximum temperature records were also set. It was also a dry month for much of the West and the combination of heat and limited moisture led to drought expansion in some regions; wildfire activity also saw a big uptick.
Below-normal precipitation occurred for much of the West except for some isolated areas in the Great Basin and parts of Arizona and New Mexico. Climatologically, July is one of the driest months in West except for the core monsoon states of Arizona and New Mexico. Most of Arizona saw below-normal precipitation with some parts receiving less than 50 percent of normal; isolated parts of the state were above normal. Southwest Montana was notably dry with monthly departures of more than one inch for some locations. Butte, Montana had its eighth driest July with just 0.19 inch of precipitation (16 percent of normal).
According to the USDM at the end of July, 29 percent of the West was in drought. Areas of extreme (D3) drought are found in southern New Mexico with D3 and exceptional drought (D4) in western Montana. Spatially, the greatest drought expansion occurred in Oregon with most of the state now in abnormally dry (D0) or moderate drought (D1). Monsoon rains have helped to reduce some of the spatial extent and severity of drought in New Mexico.
Alaska summary: Alaska saw below-normal temperatures in most of the state with anomalies generally -1 to -4 degrees Fahrenheit. The Panhandle saw near-to-slightly-above-normal temperatures. It was a wet month for most of Alaska with several long-term stations in the top ten wettest Julys.
Hawaii summary: Below-normal precipitation occurred throughout Hawaii with many stations reporting less than 50 percent of normal. Honolulu tied the record for driest July (also occurred in 2017) with 0.02 inch of precipitation (4 percent of normal) and Lihue also saw its driest July with 0.64 inch of precipitation (37 percent of normal). Hilo had its tenth driest July with 4.84 inches of precipitation (52 percent of normal). Dryness led to increased extent of drought by the end of July with 55 percent of the state in drought. Severe drought (D2) was found only on the Big Island and Molokai with no D3 or D4 present in the state.