A powerful atmospheric river storm swept across California on Christmas Eve, triggering widespread flooding, forcing hundreds of residents to evacuate, and prompting emergency declarations as authorities warned the dangerous conditions would continue through Christmas Day.

Flash flooding was reported across southern parts of the US state following torrential rainfall, with video from one mountain resort showing debris and mud cascading down roads and fast-moving water rushing through the porches of several homes.

The US National Weather Service said “life-threatening atmospheric river conditions” were expected to persist throughout Christmas Day, with a rare “high risk of excessive rainfall” warning still in effect.

According to Sky News, California Governor Gavin Newsom declared a state of emergency in six counties, a move he said would allow “emergency authorities and preposition resources to keep our communities safe”.

Los Angeles County officials said about 130 evacuation orders were issued for vulnerable homes, many located in areas that were burned by wildfires earlier in the year, raising concerns about mudslides and debris flows.

According to National Weather Service meteorologist Mike Wofford, Southern California typically receives up to 2.5cm of rain at this time of year, but many areas could see between 10 and 20cm this week, with higher totals expected in mountainous regions.

In the Sierra Nevada, heavy snow and strong gusts were forecast to bring “near white-out conditions” and make travel “nearly impossible” through mountain passes. The Sierra Avalanche Centre also warned of a “considerable” avalanche risk around Lake Tahoe.

Despite the disruption, utility provider Pacific Gas and Electric said power had been restored to more than 165,000 homes that experienced outages during the storm. (Sky News)

•Cars drive through puddles as heavy rain falls due to an atmospheric river, in an intersection in the Woodland Hills area of Los Angeles, California, U.S., December 24, 2025. REUTERS/Jill Connelly