Major storm to unload inches of rain, set off dangerous flash flooding in California
A rare setup for November will unleash two waves of heavy rain across California, with the second storm threatening to bring major flooding, mudslides, and travel chaos to Los Angeles and surrounding areas.
AccuWeather’s Ken Clark says a powerful storm system from the Pacific will bring drenching rainfall and an increased risk of flash flooding and mudslides to Southern California this weekend.
A two-part storm system is expected to bring rounds of heavy rain to California later this week and into the weekend. The second wave could produce rainfall amounts typically seen over several months in Southern California, resulting in significant travel disruptions, flash flooding and debris flows.
This image was captured on Thursday, Nov. 13, 2025, and shows one part of a Pacific storm moving onto the West Coast of the United States on the right and a second and stronger part of a storm farther west to the left. (AccuWeather Enhanced RealVue™ Satellite)
"The combination of a complex storm structure, a pronounced dip in the jet stream and abundant Pacific moisture is forecast to bring widespread drenching rain and drought relief to California," AccuWeather Chief On-Air Meteorologist Bernie Rayno said. "Unlike the typical pattern where heavier rain impacts Northern California, this system is expected to bring the most significant rainfall to coastal areas of Southern California, including Los Angeles."
1st part of storm to encompass much of California
Drenching rain will spread across most of California, which may lead to ponding on roads and increased runoff along hillsides, localized flash flooding and debris flows.
The heaviest rain has already occurred across San Francisco and Sacramento; both areas received 1-2 inches of rain from the storm.
Heavier amounts of 2-4 inches, with an AccuWeather Local StormMax™ rainfall of 6 inches, are anticipated along the coast of Northern California and along the lower, southwest-facing slopes of the Sierra Nevada through Friday.
Much of the vast interior valley of California will pick up 0.50 of an inch to 2 inches of rain from the first part of the storm into Friday afternoon.
Rain from the first part of the storm will affect Los Angeles through Friday morning and San Diego from Friday morning into midday, before a lull with spotty showers for a time afterwards.
A bit of slush for Donner Pass; Feet of snow in high country
Snow levels will be well above the passes in the Sierra Nevada for most of the storm through Friday.
Then, as colder air invades the storm prior to the end of the week, snow levels will dip to the passes at the tail end, with perhaps an inch or two of snow for Donner Pass, California, along Interstate 80 from late Thursday night to Friday morning. The heaviest snowfall, 1-3 feet, will accumulate on the high country of the central and southern Sierra Nevada from late Thursday to Friday night at an elevation above 8,000 feet.
Second part of storm to pack a wallop in Southern California
The second leg of the storm will begin Friday night and continue through Saturday and into Saturday night with torrential rain and locally gusty thunderstorms across much of Southern California.
The Los Angeles Basin could receive 2–4 inches of rain from the second wave of the storm, an amount that rivals totals typically recorded during the most formidable storms in the winter. November marks just the start of the rainiest part of the year in Southern California. The average rain for November in L.A. is 0.78 of an inch.
"The historical average annual rainfall for downtown L.A. is 14.25 inches," AccuWeather Senior Meteorologist Joe Lundberg said. "So this storm, especially when combined with the late-week rain, could equate to one-third of the annual rainfall for the city and many other areas in the region."
Hourly rainfall rates could exceed 1 inch per hour.
The heaviest rain will fall on the south- and west-facing slopes of the Transverse Ranges in Southern California. In these mountainside locations, a general 4-8 inches of rain is forecast from Friday night to Saturday night with an AccuWeather Local StormMax™ of 10 inches.
Rainfall of this intensity on the mountain slopes, as well as slightly lesser amounts in the city, the immediate coast and the deserts to the east, will lead to dangerous flash flooding and mudslides. Some roads could be washed out. Some unstable land on earthen hillsides could collapse.
The bulk of the rain from the second and more moisture-packed leg of the storm will be south of San Francisco and Sacramento.
Showers are likely to linger in Southern California Sunday.
Thunderstorms, desert downpours are coming this weekend
Thunderstorms are forecast to accompany this rain in some areas, with the strongest storms producing damaging wind gusts, hail and even a waterspout or brief tornado.
Heavy rainfall is also expected to shift eastward into the deserts of southeastern California, southern Nevada, and Arizona. These areas are expected to receive 0.50 of an inch to 2 inches of rain, with some of that rainfall potentially falling in several hours, which could lead to flash flooding. Dry streambeds, known as arroyos, may rapidly fill with water and debris, increasing the risk of flash flooding.
Showers from the first storm are expected to reach Las Vegas and Palm Springs, California, Friday. The second storm will likely bring downpours to Phoenix. All three cities and other communities in the region, including Flagstaff and Tucson, Arizona, will be at risk for flash flooding and road closures over the weekend.
Aside from the flooding dangers and travel problems, the rain will be of great benefit to the Southwest, including part of the ailing Colorado River basin, due to long-term drought.
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