Prognostic Discussion for Long-Lead Hawaiian Outlooks 
NWS Climate Prediction Center College Park MD 
830AM EDT Thu Aug 15 2024 
 
MONTHLY FORECAST DISCUSSION VALID SEPTEMBER 2024 
 
Sea-surface temperatures (SSTs) near the Hawaiian Islands (Kauai, Oahu, Maui, 
and the Big Island) have predominantly been close to the 30-year climatological 
average during the past few weeks. 
 
 
From January through July 2024, rainfall total accumulations were: 
 
Lihue Airport 22.55 inches (114 percent of average) 
 
Honolulu Airport 9.56 inches (109 percent of average) 
 
Kahului Airport 9.17 inches (94 percent of average) 
 
Hilo Airport 56.66 inches (89 percent of average) 
 
The NCEP Climate Forecast System (CFS) and other climate models of the North American Multi-Model Ensemble (NMME) generally predict near-average SSTs around the Hawaiian Islands through September 2024. Based primarily on these SST forecasts, surface temperatures are indicated to be Equal Chances (EC) of below, near, and above-normal for all the islands through September. For the September 2024 precipitation outlook, below normal precipitation probabilities are elevated for all of the island chain, as indicated by most dynamical model forecasts, and consistent with a transition from ENSO-neutral to La Niña conditions over the tropical Pacific in the near future. 
 
 
 





 
TEMPERATURE
 
 
PRECIPITATION
 
 
 
FCST
 
AVE
 
LIM
 
FCST
 
BLW
 
MEDIAN
 
ABV
 
Hilo 
 
 EC
 
76.4
 
0.5
 
B45
 
8.0
 
9.3
 
11.0
 
Kahului 
 
 EC
 
79.3
 
0.4
 
B50
 
0.1
 
0.2
 
0.5
 
Honolulu
 
 EC
 
81.8
 
0.4
 
B50
 
0.4
 
0.6
 
0.8
 
Lihue 
 
 EC
 
79.4
 
0.3
 
B50
 
1.7
 
1.9
 
2.6
 
 
SEASONAL FORECAST DISCUSSION VALID SON 2024 - SON 2025 
 
Refer to the prognostic discussion of the long-lead seasonal outlooks for the CONUS and Alaska for a description of the ENSO outlook and other climate conditions relevant to the seasonal outlook. ENSO-neutral conditions are observed over the Pacific Ocean. Equatorial SSTs are above average in the west Pacific Ocean, and near average in the east-central and below average in the eastern Pacific Ocean. Negative subsurface temperature anomalies remain at depth in the central Pacific Ocean, with slightly above-average temperatures near the surface in the western Pacific Ocean. Low-level easterly wind anomalies were observed over the east-central and eastern equatorial Pacific Ocean, while upper-level wind anomalies were easterly over the east-central equatorial Pacific Ocean and westerly over the eastern equatorial Pacific Ocean. Enhanced convection and precipitation was observed over the far western Pacific and near the Philippines. Most recent dynamical and statistical models predict ENSO-neutral to continue for the next several months, with La Nina favored to emerge during September-October-November (66% chance) and persist through the Northern Hemisphere winter 2024-25 (74% chance during November-December-January). 
 
Equal Chances (EC) for above, near or below normal temperatures are indicated for Kahului and the Big Island in SON (September-October-November) 2024, consistent with most dynamical model forecasts from the NMME and C3S. Enhanced probabilities for above normal temperatures are favored over Kahului and the Big Island from OND (October-November-December) 2024 through FMA (February-March-April) 2025, and across Honolulu and Lihue from SON 2024 to FMA 2025, supported by most of the dynamical model and statistical model temperature forecast tools. The forecast signal weakens at longer leads, therefore EC is indicated for Hawaii beginning in MAM (March-April-May) 2025 and extending through longer leads. 
 
Enhanced probabilities for below normal precipitation are forecast over the Hawaiian Islands (Kauai, Oahu, Maui and the Big Island) from ASO to SON 2024, consistent with most dynamical and statistical model forecasts. Enhanced probabilities of above-normal precipitation are predicted from NDJ 2024 to JFM 2025, consistent with impacts of a developing La Niña and dynamical model forecasts. Due to considerable uncertainty in the precipitation forecasts from dynamical and statistical models, EC is indicated over the Hawaiian Islands in OND 2024 and beginning FMA 2025 and continuing through longer leads. 
 
 
















 
Hilo
 
 
TEMPERATURE
 
PRECIPITATION
 
 
 
FCST
 
AVE
 
LIM
 
FCST
 
BLW
 
MEDIAN
 
ABV
 
SON 2024
 
 EC
 
76.2
 
0.4 
 
B40
 
24.3
 
30.2
 
40.8
 
OND 2024
 
A40
 
75.5
 
0.4 
 
 EC
 
28.3
 
34.5
 
42.0
 
NDJ 2024
 
A40
 
74.2
 
0.4 
 
A40
 
26.4
 
36.6
 
43.0
 
DJF 2025
 
A40
 
72.8
 
0.4 
 
A40
 
19.6
 
30.2
 
33.3
 
JFM 2025
 
A45
 
71.8
 
0.4 
 
A50
 
22.0
 
32.0
 
44.5
 
FMA 2025
 
A45
 
71.7
 
0.4 
 
A45
 
24.6
 
34.1
 
45.5
 
MAM 2025
 
 EC
 
72.0
 
0.5 
 
 EC
 
22.5
 
28.4
 
34.0
 
AMJ 2025
 
 EC
 
72.9
 
0.5 
 
 EC
 
21.4
 
23.7
 
29.0
 
MJJ 2025
 
 EC
 
74.0
 
0.4 
 
 EC
 
20.2
 
27.5
 
29.1
 
JJA 2025
 
 EC
 
75.2
 
0.4 
 
 EC
 
19.4
 
27.2
 
31.4
 
JAS 2025
 
 EC
 
76.1
 
0.4 
 
 EC
 
25.2
 
28.6
 
33.4
 
ASO 2025
 
 EC
 
76.4
 
0.4 
 
 EC
 
26.1
 
28.8
 
33.3
 
SON 2025
 
 EC
 
76.2
 
0.4 
 
 EC
 
24.3
 
30.2
 
40.8
 

















 
Kahului
 
 
TEMPERATURE
 
PRECIPITATION
 
 
 
FCST
 
AVE
 
LIM
 
FCST
 
BLW
 
MEDIAN
 
ABV
 
SON 2024
 
 EC
 
79.1
 
0.4 
 
B40
 
2.1 
 
3.3 
 
4.8 
 
OND 2024
 
A40
 
77.8
 
0.4 
 
 EC
 
4.2 
 
5.3 
 
8.1 
 
NDJ 2024
 
A40
 
75.9
 
0.4 
 
A40
 
5.2 
 
7.6 
 
9.5 
 
DJF 2025
 
A40
 
73.8
 
0.4 
 
A40
 
4.6 
 
6.9 
 
8.7 
 
JFM 2025
 
A45
 
72.5
 
0.4 
 
A50
 
4.2 
 
6.2 
 
8.2 
 
FMA 2025
 
A45
 
72.3
 
0.4 
 
A45
 
3.2 
 
4.1 
 
6.4 
 
MAM 2025
 
 EC
 
73.0
 
0.4 
 
 EC
 
2.5 
 
3.5 
 
4.6 
 
AMJ 2025
 
 EC
 
74.3
 
0.5 
 
 EC
 
1.2 
 
1.6 
 
2.2 
 
MJJ 2025
 
 EC
 
76.0
 
0.5 
 
 EC
 
0.7 
 
1.1 
 
1.8 
 
JJA 2025
 
 EC
 
77.7
 
0.4 
 
 EC
 
0.7 
 
1.1 
 
1.5 
 
JAS 2025
 
 EC
 
79.0
 
0.4 
 
 EC
 
0.8 
 
1.1 
 
1.6 
 
ASO 2025
 
 EC
 
79.4
 
0.4 
 
 EC
 
0.8 
 
1.6 
 
2.5 
 
SON 2025
 
 EC
 
79.1
 
0.4 
 
 EC
 
2.1 
 
3.3 
 
4.8 
 

















 
Honolulu
 
 
TEMPERATURE
 
PRECIPITATION
 
 
 
FCST
 
AVE
 
LIM
 
FCST
 
BLW
 
MEDIAN
 
ABV
 
SON 2024
 
A40
 
81.4
 
0.4 
 
B40
 
2.5 
 
4.0 
 
5.6 
 
OND 2024
 
A40
 
80.0
 
0.4 
 
 EC
 
4.4 
 
6.4 
 
8.5 
 
NDJ 2024
 
A40
 
77.7
 
0.5 
 
A40
 
3.9 
 
5.6 
 
8.8 
 
DJF 2025
 
A40
 
75.3
 
0.5 
 
A40
 
3.7 
 
5.6 
 
8.6 
 
JFM 2025
 
A45
 
73.9
 
0.4 
 
A50
 
2.1 
 
4.6 
 
7.8 
 
FMA 2025
 
A45
 
73.8
 
0.4 
 
A45
 
1.9 
 
3.2 
 
4.7 
 
MAM 2025
 
 EC
 
74.8
 
0.4 
 
 EC
 
1.8 
 
2.6 
 
3.0 
 
AMJ 2025
 
 EC
 
76.3
 
0.4 
 
 EC
 
1.2 
 
1.6 
 
1.8 
 
MJJ 2025
 
 EC
 
78.2
 
0.4 
 
 EC
 
0.8 
 
1.4 
 
1.6 
 
JJA 2025
 
 EC
 
79.9
 
0.4 
 
 EC
 
0.7 
 
0.8 
 
1.3 
 
JAS 2025
 
 EC
 
81.3
 
0.4 
 
 EC
 
1.0 
 
1.4 
 
1.7 
 
ASO 2025
 
 EC
 
81.7
 
0.4 
 
 EC
 
1.6 
 
2.4 
 
3.1 
 
SON 2025
 
 EC
 
81.4
 
0.4 
 
 EC
 
2.5 
 
4.0 
 
5.6 
 

















 
Lihue
 
 
TEMPERATURE
 
PRECIPITATION
 
 
 
FCST
 
AVE
 
LIM
 
FCST
 
BLW
 
MEDIAN
 
ABV
 
SON 2024
 
A40
 
79.1
 
0.3 
 
B40
 
9.2 
 
10.0
 
11.2
 
OND 2024
 
A40
 
77.8
 
0.3 
 
 EC
 
9.2 
 
11.7
 
15.6
 
NDJ 2024
 
A40
 
75.7
 
0.3 
 
A40
 
8.6 
 
12.1
 
16.9
 
DJF 2025
 
A40
 
73.6
 
0.4 
 
A40
 
7.5 
 
8.4 
 
14.0
 
JFM 2025
 
A45
 
72.2
 
0.4 
 
A50
 
6.5 
 
8.8 
 
13.8
 
FMA 2025
 
A45
 
72.1
 
0.5 
 
A45
 
5.8 
 
8.4 
 
9.9 
 
MAM 2025
 
 EC
 
72.8
 
0.5 
 
 EC
 
5.3 
 
6.6 
 
8.0 
 
AMJ 2025
 
 EC
 
74.2
 
0.5 
 
 EC
 
4.7 
 
5.5 
 
6.0 
 
MJJ 2025
 
 EC
 
76.0
 
0.5 
 
 EC
 
4.9 
 
5.4 
 
5.9 
 
JJA 2025
 
 EC
 
77.7
 
0.4 
 
 EC
 
4.4 
 
5.3 
 
6.9 
 
JAS 2025
 
 EC
 
79.0
 
0.3 
 
 EC
 
5.3 
 
6.1 
 
7.8 
 
ASO 2025
 
 EC
 
79.4
 
0.3 
 
 EC
 
6.2 
 
7.9 
 
8.4 
 
SON 2025
 
 EC
 
79.1
 
0.3 
 
 EC
 
9.2 
 
10.0
 
11.2
 

FORECASTER: Luke He 
 
Anomalies are based on the 1991-2020 means. 
 
CLARIFICATION: EC indicated equal chances that the predicted parameter will fall into any one of the three categories, whose boundaries are specific in the tables above. A forecast specification of EC means there is no particulate tilt of the odds toward above normal or below normal conditions in the outlook. For example A40 means a 40% chance that the average temperature or total precipitation will be in the above normal class, B40 means a 40% chance that the average temperature or total precipitation will be in the below normal class, and N35 means a 35% probability that the average temperature or total precipitation will be in the near normal class. When EC is specified, all categories are equally likely. 
 
NOTE - These outlooks are intended for use prior to the start of the valid periods. Within any valid period, observations and shorter range forecasts should be consulted. Also, this set of outlooks will be superseded by the issuances of the new set net month, on Thu Sep 19, 2024.
 
 
$$