Rare ‘high risk’ for flooding spurs evacuations in Southern California after deadly floods in Northern California

Heavy rainfall caused roads to flood in Redding, California, on Sunday. (Redding Police Dept via CNN Newsource on Monday, December 22, 2025)

(CNN) — An even more potent atmospheric river-fueled storm is on a collision course with California after a first storm triggered deadly flooding and evacuations over the weekend in Northern California.

The new storm and another after it are prompting new evacuations in the Los Angeles area’s burn scars and a rare high risk for flooding from forecasters with months’ worth of rain and life-threatening flooding expected in Southern California.

At least one person is dead after flash floods from the first storm inundated Redding, roughly 150 miles north of Sacramento, according to Redding Mayor Mike Littau, who said police and fire crews carried out water rescues Sunday.

A police officer pulled the victim from a flooded vehicle, Littau said Monday morning, though the official cause of death is still under investigation. Officials have not said how many water rescues were carried out in the city.

Shasta County, where Redding is located, was hit particularly hard Sunday evening, with heavy rain flooding multiple roadways, including parts of Interstate 5, according to officials.

Nearly a month’s worth of rain fell in the Redding area Saturday through Sunday: One of the city’s fire stations measured just over 5 inches of rain.

Redding police said they responded to “numerous calls for stranded motorists” and urged drivers to avoid flooded streets.

Paul Mast posted video of his son standing in the middle of a Shasta County road flooded by a nearby creek. Mast said they were on their way to a family Christmas gathering but had to turn around because floodwater had washed out part of the road.

Shasta County wasn’t the only area underwater on Sunday: Crews also performed water rescues in Humboldt County, where the floodwater was chest-deep in some places. There were “numerous incidents” where deputies rescued people from vehicles stalled in floodwater, a sheriff’s office spokesperson told CNN. Several homes flooded, forcing residents to evacuate, in some cases by boat and jet ski.

While the flooding is subsiding Monday, there have been reports of washed out roadways, debris flows and mudslides throughout the county, the sheriff’s office said, urging residents to stay vigilant ahead of this week’s upcoming storms.

Farther east, in Placer County, rising water on the South Yuba River prompted evacuations. Officials issued warnings for multiple properties in Cisco Grove in the Sierra Nevada on Sunday and at least nine people were evacuated from one home there, according to the Placer County Sheriff’s Office.

Early Monday, Sonoma County deputies rescued a motorist in Santa Rosa who drove into floodwater and had to climb onto the roof of their vehicle amid the rising water, the sheriff’s office said.

More flooding rain, debris flows and rock slides are widespread concerns with this week’s multiple storms. Strong winds that could potentially knock out power are also expected.

Much of California is under a flood watch until Friday.

New storms will expand serious flood threat across the entire state

Heavy, potentially flooding rain will continue to focus on Northern California into Tuesday, especially from the northern Sierra Nevada foothills into the Bay Area.

Then another, more widespread storm steps up to the plate. This strong atmospheric river is set to slam the entire state Tuesday night into Wednesday. It could bring life-threatening flooding.

A Level 4 of 4 “high risk” of flooding rain threat is in place for more than 5 million people in mountainous parts of Los Angeles, San Bernardino and Santa Barbara counties in Southern California on Wednesday, according to the Weather Prediction Center. A Level 3 of 4 risk is in place for more than 13 million others in the region.

These high risk flooding events are incredibly significant: High risks are issued on fewer than 4% of days per year on average, but are responsible for more than 80% of all flood-related damage and 36% of all flood-related deaths, WPC research shows.

Evacuation orders and warnings were issued by Los Angeles County for areas in and around burn scars in the greater Los Angeles area, including January’s Eaton and Palisades fire zones. The deadly blazes were two of California’s most destructive fires in history and burned a combined 16,246 structures, according to CalFire.

The orders are for 383 properties that sheriff’s deputies are directly reaching out to, including going door-to-door, according to the Los Angeles County Office of Emergency Management.

The torched earth of a burn scar can’t absorb water like it used to and instead repels water like concrete. When combined with intense rainfall rates, all that water can catapult downhill at breakneck speeds, along with mud and other debris with devastating effect.

Another atmospheric river will be right on the first’s heels, keeping stormy conditions locked in over the state Thursday into Friday.

Level 2 of 4 threats of flooding rain persist in much of the state on Thursday and Friday.

Rainfall totals in Southern California through Saturday could be as much as 4 to 8 inches in coastal and valley locations, while foothills and mountains see 8 to 12 inches.

To put those totals into perspective, a city like Los Angeles could see anywhere from two months’ worth of rain to nearly half a year’s worth in just a week.

The National Weather Service in Los Angeles warned of significant issues from the upcoming storms, including “widespread urban flooding, mud and debris flows and very hazardous driving conditions.”

“START TAKING PROTECTIVE ACTIONS NOW,” the NWS urged Sunday night.

Recent wildfire burn areas will be particularly prone to debris flows. Portions of the Eaton, Palisades, Hurst and Kenneth fires fall within the high risk of flooding rain area.

The abundant moisture will also fuel feet of snow farther north in the Sierra Nevada and make travel there difficult or impossible at times. It will be a big change for the region, which has had much less snow than usual to start the season.

Some relief from this nonstop stormy pattern looks to finally arrive for the upcoming weekend.

Karina Tsui, Chris Dolce, Mary Gilbert, CNN