A surge of Arctic air, reinforced lake-effect snowfall, and an atmospheric river are forecast to affect large portions of the United States from December 31, 2025, into January 2, 2026. Heavy snow is expected downwind of the Great Lakes and across parts of the Northeast, while southern California faces a flash flood risk as an atmospheric river moves onshore around New Year’s Day.
Heavy rain and snow are forecast across California and Sierra Nevada through January 4, 2026. The first wave will target southern California with subtropical moisture, followed by a stronger system forecast to bring heavy rain and snowfall across central and northern regions of the state.
Evacuation warnings were issued for Los Angeles County, California for multiple burn scars across the region as an atmospheric river brings in the threat of flash floods and debris flows through New Year’s Day.
A surge of subtropical moisture is forecast to bring moderate to heavy rain to southern and central California on Wednesday, December 31, 2025, with rain spreading north on Thursday, January 1, 2026. A stronger system with a re-intensified atmospheric river is expected to make landfall early Friday, January 2, bringing heavier precipitation along the northern and central California coast.
A high-pressure natural gas transmission pipeline ruptured near Ridge Route Road and Pine Crest Place in Castaic, Los Angeles County, at about 16:20 LT on December 27, 2025 (00:20 UTC on December 28), prompting a shelter-in-place advisory and a full closure of Interstate 5 until about 21:00 LT. SoCalGas confirmed its crews isolated the damaged section, stopped the leak, and reported no ignition or explosion.
The NWS Weather Prediction Center has issued a rare High Risk (level 4/4) for excessive rainfall across Southern California from Wednesday, December 24, through the morning of Thursday, December 25. 2025.
Extremely dangerous marine conditions are developing across Northern and Central California waters this week, the National Weather Service (NWS) San Francisco Bay Area warned on Tuesday, December 23, 2025. Storm Force winds are forecast across the coastal waters with Gale Force winds extending into San Francisco and Monterey bays beginning Tuesday morning. Seas are expected to build to near 6 m (20 feet) under the strongest winds, posing life-threatening conditions for mariners.
Winter Storm Warnings are in effect across parts of California from late December 23 through December 27, 2025, as a strong atmospheric river moves inland, bringing heavy mountain snowfall and high winds.
A strong atmospheric river is forecast to impact California from December 23 to 27, 2025, bringing widespread heavy rainfall, flash flooding, and high-elevation snow. The system is expected to produce 250 to 500 mm (10–20 inches) of precipitation in parts of the Sierra Nevada and 150 to 300 mm (6–12 inches) in the Coast and Transverse Ranges. The National Weather Service has issued high-risk alerts for flash flooding across southern California and moderate winter storm impacts over the Sierra Nevada.
One person was killed and several were rescued after torrential rain from an atmospheric river caused severe flooding in Redding, northern California, on December 21–22, 2025. Rainfall totals above 100 mm (4 inches) overwhelmed storm drains, flooded roads.
