Northern California under flood watch for Christmas week of atmospheric river storms
The National Weather Service issued a flood watch for the Sacramento area and a wide swath Northern California as a series of warm, powerful storms — driven by atmospheric rivers — threaten to bring “prolonged” rainfall, elevated river levels and potential mudslides through the Christmas holiday week.
The flood watch takes effect at 4 p.m. Saturday and continues through 4 p.m. Friday, Dec. 26. It marks the first significant flood watch of the 2025-26 water year, which began Oct. 1.
“A series of warm atmospheric rivers will bring moderate to heavy rain to the Valley, foothills, and mountains the week of Christmas,” the weather service said. “The prolonged period of rain will bring the risk of flooding to the Sacramento Valley, northern San Joaquin Valley, northern Sierra Nevada and adjacent foothills, as well as the Coastal Range.”
The watch includes urban and rural areas across the Northern and Central Sacramento Valley, the Sierra Nevada foothills, and the northern San Joaquin Valley. Cities under the weeklong watch include Sacramento, Stockton, Chico, Modesto and Redding.
Rain expected to persist all week
Forecasters warned of “excessive runoff” in flood-prone areas, including burn scars, low-lying neighborhoods, and regions with poor drainage. It also warned “mudslides and rockslides may occur in mountain and foothill areas.”
In a forecast discussion Friday, meterologists at the National Weather Service’s Sacramento office said the multi-day storm cycle ould wdeliver “generally beneficial rain” through the weekend, with minimal impacts expected initially. But the pattern is expected to intensify by midweek.
By Christmas Eve and Christmas Day, a colder and wetter system could lower snow levels to around 5,500 feet in the Sierra, potentially creating hazardous travel conditions along Interstate 80 and Highway 50. In the Valley, saturated soils and persistent rainfall could lead to flooding in low-lying neighborhoods, underpasses and near creeks and streams, forecasters warned.
Although debris flows over burn scars are not currently expected, officials cautioned that enhanced runoff below those areas remains a concern.
A bad time for big storms
Atmospheric rivers are not uncommon in California winters, but forecasters noted the timing and intensity of this year’s holiday storm cycle is unusual. The timing is similar to the 2022-23 winter season, when a string of back-to-back atmospheric rivers pounded the Sacramento region over the New Year’s holiday week, causing widespread flooding, downed trees and power outages.
Those storms forced mandatory evacuations in Wilton and parts of Elk Grove and left at least five people dead in Sacramento County. River levels surged as levees weakened under the strain of relentless rain. Wind gusts exceeded 70 mph, and tens of thousands of SMUD customers remained without power for days.
The incoming storms coincide with a record surge in holiday travel fueling an increased concern.
AAA projects more than 122 million Americans will travel 50 miles or more during the two-week period between Saturday and Jan. 1. That includes motorists on many of the capital region’s major thoroughfares connecting the Central Valley, Sierra passes and Bay Area corridors.
Could the mountains get snow?
In the Sierra, where resorts have been pained by warm weather and a snow drought so far this season, it was far from clear whether there would be enough cold air to lower snow levels.
“This system will be drawing up copious amounts of subtropical moisture from the south,” Bryan Allegretto wrote in the weather blog for Palisades Tahoe.
Allegretto said he has been nervous about the system of low pressure being too far away from California. To get more snow in California’s mountains, “we need the cold air at the center of the trough and the low to push inland,” and computer forecasting models are split on whether that will happen, he wrote.
What to expect in the forecast
Rainfall will intensify across the Sacramento region this weekend, with daily downpours expected through Christmas and well into next week, the weather service noted.
Showers are likely to begin Saturday and grow more persistent overnight, with between one-quarter and three-quarters of an inch of rain possible in the city by Sunday morning. Winds will pick up through Sunday, with gusts nearing 25 mph, and isolated thunderstorms are possible by late afternoon. Daytime highs across the Valley will hover in the mid to upper 50s, with overnight lows in the low to mid 50s.
The pattern continues Monday through Christmas Day, with near-constant cloud cover and high rain chances each day. Rain may ease at times but will remain widespread, the weather service said, with only brief breaks between systems.
Conditions in the Sierra foothills will be similar, forecasters said, with up to 2 inches of accumulation possible in some areas by Sunday.
In the Sierra, rain will dominate the weekend forecast in South Lake Tahoe, with snow levels staying above 8,500 feet through Monday. Several inches of rain are expected in the basin before colder air begins to push snow levels down by midweek.
By Tuesday night, snow levels are forecast to fall to around 7,000 feet, transitioning mountain precipitation to snow. Heavy snow is expected to develop Wednesday and continue through Christmas Day, potentially disrupting travel on U.S. Highway 50 and Interstate 80.
Forecasters warn that holiday travelers in both the Valley and Sierra should expect delays, poor visibility, and changing conditions as the week progresses.
The Los Angeles Times and The Bee’s Daniel Hunt contributed to this story.
This story was originally published December 19, 2025 at 11:27 AM with the headline "Northern California under flood watch for Christmas week of atmospheric river storms."
