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 major atmospheric river swept across Southern California from late December 24, 2025, into Christmas Day, December 25, triggering widespread flash floods, evacuations, debris flows, and power outages. Multiple counties including Los Angeles and Ventura were put under a State of Emergency. Rainfall totals reached 75–150 mm (3–6 inches) in coastal and valley areas, with up to 250 mm (10 inches) in higher terrain of Los Angeles and Ventura counties, prompting officials to urge residents to avoid travel.
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.
Three atmospheric rivers are expected to impact California between December 20 and 25, 2025, producing 250–500 mm (10–20 inches) of rain over the Sierra Nevada and 75–180 mm (3–7 inches) over southern coastal ranges. The strongest system is forecast to peak on December 23–25 with IVT values surpassing 750 kg m⁻¹ s⁻¹ and AR3–AR4 intensity.
A series of impactful atmospheric rivers is forecast to bring heavy precipitation across California from Friday, December 19, 2025, through Wednesday, December 24, with seven-day precipitation totals expected to exceed 380 mm (15 inches) in parts of the Sierra Nevada.
The Center for Western Weather and Water Extremes (CW3E) at UC San Diego forecasts above-normal precipitation for Northern and Central California between late December 2025 and early January 2026. The latest subseasonal outlook, issued on December 16, indicates high confidence in enhanced atmospheric river (AR) activity and persistent Pacific Ridge conditions during the period from December 22 to January 11, 2026.
Historic flooding in December 2025 placed Washington state in the middle of a statewide crisis, with impacts ongoing and damage assessments still underway as of December 17. Prolonged heavy rainfall has inundated communities, damaged levees and transportation infrastructure, and forced large-scale evacuations across multiple counties. At least one person died after driving into deep floodwaters.
