California wildfires fueled by months of unusually extreme weather

Fast-moving wildfires in the Los Angeles area are burning out of control long after the fire season normally ends in California. Strong Santa Ana winds are not unusual this time of year, but they have arrived after months of drought. The combination has led to a catastrophic series of fires, a possible indication of how climate change is changing the way fires behave in the state.

“While the Santa Ana fires are nothing new in Southern California, this type of explosive fire event has never happened in January before, and it has only happened once in December,” said Crystal Kolden of the University of California, Merced.

As of Jan. 8, at least four wildfires were burning in the Los Angeles area, according to the California Department of Forestry and Fire Protection. The two largest fires are the Palisades Fire and the Eaton Fire, each of which has burned more than 4,000 hectares (10,000 acres) in one day. The fires have killed at least two people and destroyed at least a thousand homes, as well as forcing tens of thousands of people to evacuate. The fires also threatened NASA’s Jet Propulsion Laboratory and the Getty Museum.

Strong Santa Ana winds have reached speeds of up to 129 kilometers (80 miles) per hour, fanning the flames and fueling their rapid spread. The windstorm is expected to be the most intense since 2011, with “extremely critical fire weather conditions” expected to continue through the afternoon of Jan. 8, according to the US National Weather Service. The fire weather could continue as late as January 10, challenging firefighting efforts.

This is the latest in a “very highly unlikely sequence of extreme climate and weather events” that contributed to the intense fires, says Park Williams of the University of California, Los Angeles (UCLA). Santa Anas are a regular feature of Southern California weather, but wet fall and winter weather usually limits their influence on fires. This year, the rainy weather has still not arrived, leaving the vegetation parched and ready to burn. Additionally, there is more vegetation for fuel thanks to a wet winter in 2023 that spurred growth. Intense heat and drought throughout 2024 dried it out.

The combination of lots of fine fuel, drought and strong, hot, dry winds produces “the most explosive fire behavior imaginable,” Kolden says.

Officials are still investigating what ignited the flames. It will also take some time to understand the role that climate change may have played. However, there is reason to believe that this has made the fires worse.

Above-average sea surface temperatures in the Pacific, likely driven in part by climate change, have also contributed to the dry conditions. According to Daniel Swain at UCLA, these higher ocean temperatures have created a ridge of high pressure that has blocked wet weather carried on the jet stream from reaching Southern California.

The region has seen this type of high-pressure weather system occur more frequently over the past fifty years, which may be a symptom of climate change, says Daniel Cayan of the University of California, San Diego.