Millions in California are under flood alerts as intense downpours threaten Christmas travel

Residents of Los Angeles spent the day before Christmas under rain showers and winds of around 40 mph, while the New England area braces for heavy snow later in the week.

More than 40 million people were under flood alerts Wednesday morning, including most of California, as well as parts of southern Nevada and western Arizona. The heavy rain triggered numerous flash flood warnings in and around Los Angeles County.

California Gov. Gavin Newsom declared a state of emergency for Los Angeles, Orange, Riverside, San Bernardino, San Diego and Shasta counties.

He said the order will “activate emergency authorities and preposition resources to keep our communities safe.”

“We’re expecting continued impacts into the weekend,” Courtney Carpenter, a meteorologist with the National Weather Service office in Sacramento, said in a video shared by the state’s emergency agency.

The storm is an “atmospheric river,” she said. As much as 1 to 1.5 inches of rain per hour is expected, increasing the risk of debris flows, mudslides and flash flooding over the Palisades and Eaton fire burn scars.

Wind gusts could lead to tree damage, wire damage and power outages.

The beach in Santa Monica recorded a wind gust of 39 mph Wednesday, the National Weather Service said, and the hills around Ventura saw a gust of 69 mph.

In the Sierra Nevada, traffic was being turned around on westbound Interstate 80 at the Truckee and Donner Lake interchange due to multiple spinouts, the California Department of Transportation said.

“Conditions are going downhill quickly over the Sierra as heavy snow continues and snow levels are dropping. Travel over the mountains is highly discouraged as heavy snow will continue through Friday!” The National Weather Service office in Sacramento said on X.

In the San Bernardino area, east of Los Angeles, the California Department of Forestry and Fire Protection shared video online showing rushing water at Sheep Creek and Phelan roads. It urged caution and warned motorists to never drive through flooded roads.

“Arriving safely is always worth the extra time,” the agency’s San Bernardino unit said on X.

Overnight, the heavy rain will taper off, but another round will roll through Thursday. It is expected to bring a higher risk of strong to severe thunderstorms and isolated tornadoes.

Travelers will see much calmer weather in other parts of the country. Sunny skies are expected in the Southeast, record warmth is sweeping across the middle of the country, and the Midwest to the mid-Atlantic and Northeast will see dry skies.

On Christmas Day, flooding and strong thunderstorms continue in California.

A quick-moving storm will hit the Northeast on Friday, leading to a widespread 4 to 8 inches of snow across much of New York, northern Pennsylvania, southern New England and northern New Jersey. Winter alerts have been posted for at least 33 million people ahead of the winter storm.

In Baltimore, Philadelphia and Washington, D.C., there will be a mix of snow, rain and ice.