Three dead as California hit by a series of storms over Christmas period.

Three people have died and many others have been affected by flooding as California has been hit by a series of storms over the Christmas period. A 74-year-old man from Redding, in Shasta County, died on the weekend of 20-21 December 2025, after his car became trapped in floodwaters, despite efforts by local police officers to rescue him. On Monday 22 December a woman in her 70s died after being swept into the sea by a large wave at MacKerricher State Park in Mendocino County. On Wednesday 24 December a 64-year-old man from San Diego was struck by a falling tree.

A car partially buried by a mudslide in San Bernadino County, California. CBS News.

Many areas have been affected by flooding, with some communities in San Bernadino County facing evacuation orders in order to keep them safe. Several flash floods have been reported in Los Angeles County, where 27 cm of rainfall was recorded on Wednesday 24 December, with a large landslip reported in Altadena, on a slope which had been stripped of vegetation by wildfires in January this year. Around 130 households were evacuated due to concerns about flooding and landslides in Los Angeles, mostly in the Pacific Palisades neighbourhood, which was also hit by wildfires in January. Windspeeds gusting in excess of 100 km per hour have been recorded in San Francisco, where waves more than 7 m high have been reported. More than 100 000 people have been left without power due to the storms, mostly in the central part of the state.

The storms have been driven by a phenomenon called an atmospheric river, in which a narrow band of saturated air carries large volumes of moisture for long distances. Such streams typically originate in tropical regions, and typically travel along the boundaries between diverging weather systems. As with other storm systems, once they pass over land they lose momentum, and can be forced upwards by hills or mountains, causing them to cool and deposit their moisture as precipitation, causing high rainfall and often flooding.

A diagrammatic representation of an atmospheric river. National Weather Service/National Atmospheric and Oceanic Organization/Wikimedia Commons.

Atmospheric rivers are a common phenomenon on the west coast of the United States, and a significant driver of local weather conditions. However, these systems are becoming both more common and more severe as a result of the warming climate, which has led to rising temperatures over the tropical Pacific, and subsequently higher levels of atmospheric moisture, combined with a tendency form storm systems and other weather events to form and move much more quickly, making it harder for meteorologists to make long term predictions about where and when such storms will hit.

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Wildfires kill at least 40 in California.

Forty people have died and many more are missing in a series of wildfires that have swept across California's Napa Valley this week. At least fifteen fires are still burning across the northern part of the state, where over 890 square kilometres of farmland and 5700 buildings have been destroyed. More than 10 000 firefighters from California and neighbouring states are currently fighting the fires.

Fires burning in Peters Canyon Regional Park in Orange County, California, earlier this week. Irfan Khan/Los Angeles Times.

The worst of this fires is in Sonoma County, where an incident named the Nuns Fire, started by a downed power line hitting  tree, has destroyed almost 200 square kilometres of land have been burned and the outskirts of the cities of Sonoma and Santa Rosa affected, and a second incident, the Tubbs Fire, so called because it started near Tubbs Lane near the city of Calistoga has destroyed over 140 square kilometres of land between Calistoga and Sonoma, resulting in 22 deaths.

 Burning buildings to the east of Healdsburg in Sonoma County earlier this week. J Morris/San Francisco Chronicle.

In Mendocino County a fire named the Redwood Fire has destroyed around 130 square kilometers of land and destroyed around 90 buildings. Eight people are understood to hav edied on the first day of this fire, prompting the evacuation of a further 5000 from homes in its path. A further six people have died and a further 76 are missing in Napa County, where a blaze called the Atlas Fire has destroyed around 200 square kilometers of land, including much of the county's winelands. In Yuba County four people have died in the Cascade Fire, which has destroyed around 40 square kilometres of land.

The remains of the Signorello Estate Winery in Napa County, California, destroyed by wildfires this week. Justin Sullivan/Getty Images.

The fires have a variety of causes and have been fueled by dry winds blowing from the mountains in the northeast of the state, but are essentially due to a prolonged drought in the state, which has been experiencing dry conditions since 2011, the longest such drought in the state's recorded history. This drought has killed vegetation, including thousands of trees, across much of central California, providing dry tinder to fuel the fires, despite high rainfall that caused flooding in parts of the state in the winter of 2016-7. The draught has been made worse by the diversion of water to suit Human purposes, such as agriculture, industry and leasure, which has taken water away from other ecosystems, resulting in the build-up of dead, dry vegetation that has produced fuel for the fires.

Dry vegetation near Shandon in San Luis Obispo County, California, in May 2015. Al Seib/Los Angeles Times.

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Magnitude 3.0 Earthquake in Mendocino County, California.

The United States Geological Survey recorded a Magnitude 3.0 Earthquake at a depth of 6.4 km, roughly 7 km to the northwest of the town of Laytonville in Mendocino County, California, slightly before 6.30 pm local time on Friday 25 October 2013 (slightly before 1.30 am on Saturday 26 October GMT). This is not a large quake, and there are no reports of any damage or injuries, though it was felt as far away as Eureka, approximately 130 km to the northwest of the epicenter.

The approximate location of the 25 October 2013 Mendocino County Earthquake. Google Maps.

California is extremely prone to Earthquakes due to the presence of the San Andreas Fault, a tectonic plate margin that effectively bisects the state. The west of California, including Santa Barbara and Los Angeles, is located on the Pacific Plate, and is moving to the northwest. The east of California, including Fresno and Bakersfield is on the North American Plate, and is moving to the southeast. The plates do not move smoothly past one-another, but constantly stick together then break apart as the pressure builds up. This has led to a network of smaller faults that criss-cross the state, so that Earthquakes can effectively occur anywhere.

Witness accounts of Earthquakes can help geologists to understand these events and the underlying structures that cause them. If you felt this quake (or if you were in the area but did not, which is also useful information) then you can report it to the United States Geological Survey here.

See also Magnitude 2.6 Earthquake in northeast Sonoma County, California, Magnitude 2.5 Earthquake in northwest San Benito County, California, Magnitude 2.8 Earthquake in San Benito County, California, Magnitude 4.5 Earthquake off the coast of northern California and Magnitude 3.4 Earthquake in northern California.

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