California About to Get Hit With 'Biggest Storms' of Winter

The two "biggest storms of winter" will slam into California this weekend back-to-back, fueling fears of life-threatening floods for several cities.

The first of two atmospheric rivers began moving through the state on Thursday and brought wind and rain. Meteorologists are more concerned about the second storm, which will make landfall on Sunday and continue into Monday. Preliminary forecasts are predicting concerningly high rainfall amounts, particularly in southern California, prompting meteorologists to urge people in some areas to begin preparing.

Atmospheric rivers are defined as a "long, narrow region in the atmosphere—like rivers in the sky—that transport most of the water vapor outside of the tropics," according to the National Oceanic and Atmospheric Administration. More than a dozen atmospheric rivers battered the state last year, largely eliminating drought but creating severe problems such as flooding and mudslides.

AccuWeather called the storms the two "biggest storms of winter".

The first storm produced 1 to 4 inches of rain across much of northern California before moving southward and bringing similar amounts to southern California. Snow is still expected to fall in the Sierra Nevada mountains on Friday, but AccuWeather senior meteorologist John Feerick said much of the storm has passed the Golden State.

However, the second storm is looming off the West Coast and will arrive on Sunday.

AccuWeather senior meteorologist Adam Douty told Newsweek that the storms' paths through California aren't uncommon but having two "fairly significant systems" within a week "doesn't happen all that often."

The second storm will be a prolonged event, bringing multiple days of rain and snow to the region.

"The area of particular concern is the mountains in Southern California outside the LA basin," Douty said, adding that the mountains could receive 8 to 12 inches of rain, with 4 to 8 inches forecast for Los Angeles.

Rainfall totals in February average 3.76 inches for Los Angeles.

"It's very possible that LA could see their entire February's worth of rain over the course of two days," Douty said.

The National Weather Service (NWS) office in Los Angeles shared a forecast map of the expected rain in southern California from the second storm on X, formerly Twitter, on Thursday night.

"These are very high amounts. Life threatening and damage flooding is possible," NWS Los Angeles posted with the map.

Forecasts predict more than 5 inches of rain for Los Angeles, more than 9 inches of rain for Ojai, nearly 6.5 inches of rain for Santa Barbara and 6.3 inches of rain for Pasadena.

Since the second storm is following the first so closely, flooding could be "more extensive and much worse" than the first storm, AccuWeather reported.

"Expect major urban and small stream flash flooding as well as significant rises on some of the larger rivers in the region with flooding in unprotected areas," the report said.

The atmospheric rivers follow devastating flooding that occurred in San Diego last week, in which the typically dry city saw more than 2 inches of rainfall in six hours. Destruction was so severe that Governor Gavin Newsom declared a state of emergency for San Diego and Ventura counties.