A powerful atmospheric river is set to soak large parts of California through Christmas Eve and Christmas Day, raising serious concerns about flooding, mudslides and dangerous travel conditions. Forecasters warn the storm could deliver months’ worth of rain in just a few days, hitting at the worst possible time for holiday travel.
A rare storm, landing at the worst moment
The storm system is often called a “Pineapple Express” because it draws moisture from near Hawaii. It began pushing into California late Tuesday and is expected to intensify overnight into Wednesday.
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According to the National Weather Service, storms of this strength typically hit the region only once every five to ten years. What makes this one stand out is its timing.
“This is the type of storm system that affects the area approximately every 5 to 10 years or so,” said Ariel Cohen, meteorologist in charge at the National Weather Service. “But what makes this storm unique is that the brunt of the rainfall is expected to occur right through Christmas Eve and Christmas Day.”
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Flooding risks stretch across the state
Heavy rain has already caused flooding in parts of Northern California, including Redding and Willits, after a weekend storm killed at least one person.
In Southern California, the Weather Prediction Center has issued a rare “high risk” designation for excessive rainfall on Christmas Eve across parts of Los Angeles, Ventura, San Bernardino and Santa Barbara counties. High-risk designations are issued on fewer than 4% of days each year, but account for the vast majority of flood-related damage nationwide.
Forecasters warn that rainfall rates could exceed an inch per hour at times. The rate is more than enough to overwhelm storm drains and trigger flash flooding.
Mudslides, burn scars and dangerous roads
Officials are especially concerned about recent burn areas, where scorched ground can repel water and rapidly turn rainfall into fast-moving debris flows. Evacuation warnings and orders are already in effect in parts of Los Angeles County, including areas near the Palisades and Eaton fire zones.
Urban flooding is also expected to be widespread, with rockslides and mudslides likely in mountainous terrain and along major roadways.
“With as much total rain as what we’re expecting, widespread, significant flooding will likely occur,” Cohen said. “If you’re planning to be out on the roads during the Christmas holiday, please reconsider your plans.”
Closures, evacuations and holiday disruptions
Several Southern California ski resorts have announced closures through Christmas due to the storm, citing safety concerns for guests and staff. Officials across the region are urging residents to avoid unnecessary travel, monitor evacuation alerts, and be prepared for power outages caused by strong winds and saturated soil.
Governor Gavin Newsom has mobilized state resources ahead of the storm, with crews and equipment pre-positioned across affected areas.
Forecasters say the threat may not end with Christmas. Another storm system is expected to follow later this week, extending the risk of flooding and travel disruptions into the days after the holiday.
