Atmospheric River Slams Los Angeles, California and San Francisco, California on Christmas Day

A Christmas Day Storm Takes Hold

Another powerful storm driven by an atmospheric river struck California on Christmas Day, bringing flooding rain, violent winds and heavy mountain snow. The storm arrived after a damaging Christmas Eve, compounding impacts across much of the state.

In Northern California, a line of severe thunderstorms moved in early Christmas morning. Wind gusts exceeded 70 mph. Heavy rain triggered flash flooding across the San Francisco Bay Area. Streets filled quickly. Water pooled where it had nowhere else to go.

In Southern California, the rain continued to fall on already saturated ground. Flood risk remained high through Friday. Authorities warned conditions could deteriorate rapidly.

Record Rainfall and Rising Flood Risk

Downtown Los Angeles, CA recorded its wettest Christmas Eve to Christmas Day period since 1971, according to the National Weather Service office in Los Angeles. Many other locations across Southern California also set new rainfall records.

Some mountain areas north and northwest of Los Angeles had already received between 4 and 8 inches of rain. Additional rainfall was forecast through Friday, increasing the risk of flooding as runoff intensified.

Rainfall totals by the end of the week were projected to reach:

• 4 to 7 inches in coastal and valley areas
• 6 to 14 inches in foothills and mountain regions

Forecasters noted that Los Angeles could receive the equivalent of several months of rain in just one week.

Evacuations and Rescues in Mountain Communities

The mountain resort community of Wrightwood, CA, in the San Gabriel Mountains, was among the hardest hit. Flooding, mudslides and debris flows inundated the area, prompting shelter in place and evacuation orders.

Fire officials said Highway 2 was overwhelmed by water and mud. Some residents were rescued from flooded vehicles. Others were airlifted from rooftops by helicopter.

San Bernardino County Fire spokesman Eric Sherwin described the situation plainly:
“The city got so much water and so much mud. The safest thing for residents to do was to shelter in place."

Roughly 120 emergency personnel worked through Christmas Eve into Christmas Day assisting residents. One child suffered minor injuries. No fatalities were reported in Wrightwood.

Burn Scars Amplify the Threat

Mudslides and debris flows posed a major threat in areas scarred by recent wildfires. Burned ground repels water rather than absorbing it, turning intense rainfall into fast moving floods of mud and debris.

Evacuation orders were extended in burn scar zones across Los Angeles County until Friday afternoon. Officials warned that even moderate rainfall could trigger dangerous conditions.

The National Weather Service issued multiple flash flood warnings across Santa Barbara County, Ventura County and San Mateo County, citing rain rates of up to 0.60 inches in 30 minutes.

High Winds, Power Outages and Infrastructure Damage

Strong winds accompanied the storm statewide. In Northern California, gusts reached 108 mph in the hills above the Bay Area. In Southern California, winds topped 90 mph in parts of the San Gabriel Mountains.

Power outages spread quickly. More than 60,000 Pacific Gas and Electric customers in Northern California lost electricity, with statewide outages approaching 70,000.

Infrastructure disruptions mounted:

• Interstate 80 through the Sierra Nevada operated under chain controls
• Portions of Interstate 5 and Interstate 15 were shut down due to flooding and debris
• Santa Barbara Airport, CA closed after floodwaters covered runways

In San Francisco, CA, flash flooding prompted Waymo to temporarily suspend its self driving taxi service.
“Given the critical severity of the flash flood warning early this morning, we temporarily paused our service in the San Francisco Bay Area," a Waymo spokesperson said.

Weather Related Deaths Reported

At least two deaths were attributed to weather related incidents during the storm.

In Sacramento, CA, a sheriff’s deputy died after losing control of his vehicle on a wet roadway while driving to work. Authorities said heavy rain had fallen shortly before the crash.

In San Diego, CA, a 61 year old man was killed when a large tree branch fell during high winds. Fire officials said family members were unable to help as the branch pinned him.

His daughter in law described him in an interview as an “elderly, loving man" who “was always helping his family."

Emergency Declarations and Ongoing Warnings

California Governor Gavin Newsom declared a state of emergency in Los Angeles, Orange, Riverside, San Bernardino, San Diego and Shasta counties. The declaration allowed emergency resources to be deployed more rapidly.

Los Angeles Mayor Karen Bass also declared a local emergency, stating the move ensured city departments had the resources needed in the days ahead.

Despite evacuation orders in parts of Ventura County, Santa Barbara County, Orange County and San Bernardino County, officials acknowledged that some residents chose not to leave. Los Angeles Police Chief Jim McDonnell said many residents remained in place even after deputies went door to door.

Snow Piles Up in the Sierra Nevada

While rain battered lower elevations, heavy snow fell across the Sierra Nevada. Travel became difficult and at times impossible.

Over a 48 hour period:

• Northstar ski resort reported 38 inches of new snow
• Kirkwood recorded 33 inches
• Heavenly received 28 inches

The UC Berkeley Central Sierra Snow Lab measured 23.6 inches in 24 hours, with another 2 to 3 feet expected. Avalanche warnings were issued for the greater Lake Tahoe region and the eastern Sierra due to unstable snowpack and strong winds.

The storm continued into Friday. Relief was not expected until the weekend.