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.
At least three people have been killed by severe floods and landslides in Spain between December 28–29, 2025.
Severe Tropical Cyclone Hayley is forecast to make landfall over the northern Dampier Peninsula, Western Australia, late on Tuesday, December 30, 2025, as a Category 3 system. The cyclone is expected to bring destructive winds, heavy rainfall, and flash flooding across parts of the west Kimberley coast.
Multiple tornadoes, including an EF-1 with peak winds of 158 km/h (98 mph), touched down in Illinois on Sunday, December 28, 2025, with significant damage and power outages being reported across Tazewell, Christian, and Macon counties.
The Iowa State Patrol responded to 31 crashes during extreme winter weather on December 28, 2025, as snow, high winds, and whiteout conditions spread across the state. One person was killed, and several others were injured while visibility dropped to near zero on major highways, including Interstate 35.
A powerful winter storm named Johannes swept across the Nordic countries over the weekend, killing three people in Sweden and leaving hundreds of thousands without electricity across Sweden, Norway, and Finland. Sweden’s Meteorological and Hydrological Institute (SMHI) issued widespread alerts for strong winds as the system moved north. The storm, known as Hannes in Finland, also caused major travel disruptions, grounding flights and halting rail and ferry traffic.
A powerful bomb cyclone is forecast to strike Ontario bringing heavy snow, freezing rain, and severe winds from Sunday through Tuesday, December 28 to 30, 2025, as the deepening low crosses the Great Lakes. Environment and Climate Change Canada has issued Winter Storm and Freezing Rain Warnings, with snowfall totals of up to 50 cm (20 inches) and gusts exceeding 100 km/h (62 mph) expected in some areas.
