The Weather and Climate Influences on the January 2025 Fires Around Los Angeles
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Highlights
- A trifecta of fire-friendly climate conditions set the stage for the January 2025 fires: back-to-back wet winters that boosted vegetation, a record-dry fall, and an extremely strong Santa Ana wind event.
- By one estimate, record-low fall precipitation had a bigger influence on the exceptionally low vegetation moisture than the near-record summer and fall temperatures.
- A preliminary attribution analysis concluded that long-term global warming and the development of La Niña contributed roughly equally to making the extreme fire weather conditions more likely and more extreme.
- The most effective near-term strategies to lower risk are controlling unwanted human ignitions under high-risk conditions, using fire-resistant building materials and landscaping, and locating development in lower-risk areas.
On January 7, 2025, a handful of wildfires erupted in the Los Angeles metro area and raced through multiple neighborhoods, killing more than two dozen people, razing upwards of 15,000 homes and businesses, and creating unhealthy air quality for millions of people. Based on preliminary estimates, the two largest blazes—the Eaton Fire and the Palisades Fire—have already moved into the second (Eaton) and third (Palisades) spots on California’s list of most destructive fires on record.
The fires around Los Angeles were the result of the dangerous overlap of multiple human and natural influences. The fire ignitions were human-caused—like virtually all winter fires in the area—although the exact trigger remains under investigation. How destructive they became has a lot to do with population density and building patterns that position homes and other vulnerable assets shoulder to shoulder with the region’s grass and shrub-dominated chaparral landscapes.
On the weather and climate side, there were record-amounts of flammable vegetation—what fire scientists call “fuel load”—due to extreme wetness followed by extreme heat and record dryness. The landscape was primed for explosive fire. And then extreme Santa Ana winds started to blow down from the Great Basin.
