The Weekly Volcanic Activity Report: December 10-16, 2025
New activity/unrest was reported for 5 volcanoes from December 10 to 16, 2025. During the same period, ongoing activity was reported for 17 volcanoes.
Over 700 landslides and avalanches mapped after M7.0 2025 Hubbard Glacier Earthquake
A strong M7.0 oblique-slip earthquake struck beneath the Hubbard Glacier in the St. Elias Mountains, about 89 km (55 miles) north of Yakutat, Alaska, at 11:40 AKST (20:40 UTC) on December 6, 2025. The quake triggered widespread ground failures, with over 700 landslides and snow avalanches identified across Alaska and Canada. The largest and most concentrated slope failures occurred within a 16 km (10 miles) wide band along the estimated fault rupture.
Blizzard warnings in effect for parts of North Dakota, Montana, and Minnesota, U.S.
Blizzard Warnings are in effect across parts of Montana, North Dakota, and Minnesota through Thursday, December 18, 2025, due to a fast-moving winter storm producing widespread blizzard conditions and destructive winds across the region.
Blizzard conditions and destructive winds forecast for the northern Plains and northern Rockies, U.S.
A fast-moving winter storm is forecast to bring widespread blizzard conditions and destructive winds across parts of Montana, North Dakota, and Minnesota through Wednesday night into Thursday, December 17 into 18, 2025. The system, driven a deep low-pressure trough, is generating gusts up to 110 km/h (70 mph) and localized peaks over 130 km/h (80 mph) in leeward mountain areas, potentially leading to whiteout conditions, road closures, and power outages across the region.
Above-normal atmospheric river activity forecast for Northern and Central California in late December
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.
Powerful windstorm leaves 300 000 without power in Lower Mainland, British Columbia
A powerful windstorm left over 120 000 customers, an estimated 300 000 people, without power on Wednesday, December 17, 2025, after winds of up to 90 km/h (56 mph) hit parts of the Lower Mainland.
Weak La Niña to end as ocean warming signals new El Niño phase in 2026
Forecast models suggest that El Niño conditions are likely to develop during 2026, marking a shift from the ongoing weak La Niña. The transition is expected to influence jet stream patterns and temperature anomalies across the United States, Canada, and Europe, potentially reshaping rainfall distribution and winter storm activity in the Northern Hemisphere.
Strong Alberta Clipper to bring up to 40 cm (16 inches) of snow and flash freeze across northern Ontario, Canada
A strong Alberta Clipper storm will move through northern Ontario on Thursday and Friday, December 18 and 19, 2025, dropping 20–30 cm (8–12 inches) of snow, gusts up to 80 km/h (50 mph), and a sharp temperature drop. The system will create blowing snow and flash-freeze conditions on major highways, including routes between Kenora and Thunder Bay.
Powerful winter storm leaves over 1.5 million people without power across Washington, Oregon, and Idaho
A powerful winter storm hit the Pacific Northwest and parts of the inland Northwest on December 17, 2025, causing widespread power outages across Washington, Oregon, and Idaho. At least 596 830 electricity customers were left without power, an impact estimated to affect approximately 1.4–1.6 million people across the region, as strong winds damaged power infrastructure and disrupted services.
Washington state in the middle of a historic crisis as flooding impacts continue
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.
