California was walloped Monday by a powerful winter storm carrying treacherous thunderstorms, high winds and heavy snow in mountain areas.

Millions of Los Angeles County residents faced flash flood warnings as rain pounded the region and people in some areas scarred by last year’s devastating wildfires were under an evacuation warning through Tuesday because of the potential for mud and debris flows.

Los Angeles Mayor Karen Bass ordered emergency crews and city departments to be ready to respond to any problems.

The storm wreaked havoc on roadways spanning from Sonoma County to the Sierra Nevada. Traffic was halted temporarily in both directions on I-80 near the Nevada state line due to spinouts and crashes, the California Department of Transportation reported. In Santa Barbara County, a large tree toppled onto US-101, shutting down southbound lanes.

Forecasters said the western slope of the Sierra Nevada, northern Shasta County — including portions of Interstate 5 — and parts of the state’s Coast Range could see up to 8 feet (2.4 meters) of snow before the storm moves through late Wednesday. The heavy snow, wind and low visibility could also make travel conditions dangerous to near impossible, forecasters added.

“It has seemed ‘spring-like’ for a large part of 2026, but winter is set to show it’s not quite done yet,” the Shasta County Sheriff’s Office said in a social media post urging residents to stay aware of the storm.

California’s Office of Emergency Services said it was placing fire and rescue personnel and resources in areas most at risk for flooding, mud and debris flows.

Other states on Monday braced for different threatening weather events. Residents in parts of eastern Colorado received warnings that they could be in fire danger due to a combination of abnormally high temperatures, gusty winds and dry conditions. The risks were expected to continue further into the week as gusts up to 60 mph (96 kph) are likely to hit the Colorado eastern plains on Tuesday. Parts of Texas, New Mexico and Kansas were also under red flag warnings.

The latest storm comes amid a snow drought across much of the American West, with snow cover and depth measuring at the lowest levels scientists have seen in decades. Most states saw half their average precipitation or less in January, though California fared better others due to heavy rains in December.

Kashawna McInerny, a realtor in the mountain community of Wrightwood, about 80 miles (130 kilometers) northeast of Los Angeles, on Monday said she was still dealing with several tons of rock and debris on her property from Christmas and New Year’s storms that pummeled the community. After the last one, she said she got help trenching part of her side yard to direct stormwater down the street and placed a barrier of metal and wood by a door in hopes of keeping out mud and debris.

“We’re not panicking yet. At least I’m not,” she said with a laugh.

(AP)