A major Pineapple Express storm could deliver one of Southern California’s stormiest Christmases in recent memory.
The strong atmospheric river storm is expected to bring “copious amounts of rain across much of the area along with very strong winds at times,” the National Weather Service’s Oxnard office warned Monday morning.
Rainfall from the system — and concerns about flooding — had already started across Northern and Central California on Monday, and was expected to materialize in the Southland by Tuesday, kicking off what meteorologists expect to be five straight days of precipitation.
Rich Thompson, a meteorologist at the National Weather Service, said this would easily become the region’s biggest storm of the season, with the possibility of setting several records.
“This one will definitely be up there when it’s all said and done,” Thompson said, calling it one of the “more impressive Christmas Eve or Christmas Day storms.”
Almost all of California has been placed under a flood watch or will be by Tuesday. The flood watch will begin for much of Southern California on Tuesday and end Wednesday night, but most of Central and Northern California will remain at risk through Friday.
“Please take the necessary protective actions as flooding and debris flow will be a major issue this upcoming week,” the weather service warned. By Saturday, rainfall totals across Southern California’s coast and valley areas could reach 4 to 8 inches, with up to — and over — 12 inches of rain possible across the foothills and mountains.
Snow will be less of a concern in the Southern California mountains, though some ski resorts are forecast to get some fresh powder by Christmas Day.
But across the Sierra Nevada, heavy snowfall — with 3 to 5 feet falling this week — will create “major impacts to mountain travel,” the weather service warned.
The basics
- The storm is expected to deliver 4 to 8 inches of rain between Tuesday and Saturday throughout most of Los Angeles County, Orange County and the Inland Empire.
- The high desert could see 2 to 3 inches of rain. But the most precipitation — 6 to 12 inches — is expected to fall over parts of Southern California’s mountain ranges, which could trigger mudslides and debris flows in recent burn scars.
- Between Tuesday and Thursday, numerous areas have a high chance of seeing 3 or more inches of rain. There’s a 77% chance of that occurring in Anaheim and Yorba Linda, a 74% chance in Santa Ana, a 73% chance in Ontario, a 71% chance in Mission Viejo, a 69% chance in Irvine, a 68% chance in Chino, a 65% chance in Laguna Niguel and a 60% chance in San Clemente.
- There’s an 80% chance downtown Los Angeles will get 2 or more inches of rain from Tuesday through Christmas Day. The last time downtown got 2 or more inches of rain over Christmas Eve and Christmas Day was in 1971.
There is the potential for a major Atmospheric River storm system to impact the region this holiday week. Here are the latest details on rain amounts and potential impacts. pic.twitter.com/Imbvw8Ab3C
— NWS Los Angeles (@NWSLosAngeles) December 20, 2025
Timing
Tuesday: Rain begins in the region, getting worse through the day and night. Winds will also pick up throughout the day, hitting speeds between 40 and 60 mph in the L.A. and Ventura County mountains, with 80 mph gusts possible.
Wednesday: The latest weather models show the region’s heaviest rainfall totals — from a half an inch to 1 inch per hour — could occur between midnight Tuesday and noon Wednesday.
Thursday: Rain continues on Christmas Day, but with less intensity in the afternoon and evening.
Friday and Saturday: Some rain will still be possible.
