Editor’s Note (1/8/25): This story is being updated as the situation unfolds.
Another explosive wildfire in California, driven by the region’s notorious Santa Ana winds, has burned hundreds of buildings and has forced thousands to evacuate from their homes. The Palisades Fire began at 10:30 A.M. local time on Tuesday near Los Angeles’s Pacific Palisades neighborhood. Much of the neighborhood is under evacuation orders, which extended to northern Santa Monica. As of Wednesday afternoon, the fire had scorched more than 11,000 acres and destroyed more than 1,000 structures.
Another blaze, the Eaton Fire, erupted on Tuesday evening in Altadena, Calif., just north of Los Angeles. As of late Wednesday morning, it had burned more than 10,000 acres and resulted in at least two deaths. Both fires had caused numerous injuries, according to officials.
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Forecasters had warned that the risk of fire was extremely high this week, reaching “particularly dangerous situation” status as the ferocious winds combined with tinder-dry vegetation after a lack of rain during the beginning of what would usually be the wet season.
Gusts around the Palisades Fire were measured in the range of 40 to 50 miles per hour as of Tuesday afternoon, climate scientist Daniel Swain said during one of his regular “virtual climate and weather office hours,” hosted on YouTube. “Right now the winds are not extremely high, but again, they’re high enough,” said Swain, who is at the University of California Agriculture and Natural Resources. Gusts were expected to reach 70 to 80 mph as the winds would peak on Tuesday night into Wednesday, with some places potentially seeing gusts as high as 100 mph. Gusts of 99 mph was measured in the San Gabriel Mountains north of Pasadena, Calif.
The Santa Ana winds commonly propel fast-moving, damaging fires in this area; their characteristic dryness and speed can rapidly fan and spread flames. These winds are a result of local geography and a particular meteorological setup in which a high-pressure system sits over the Great Basin in the interior of the U.S. West and a low-pressure system hangs over California or offshore. Winds “want” to move from high to low pressure, and as they do so in this area, they travel downslope from the relatively high deserts. This descent compresses the air, warming it up and drying it out. (Such downslope winds, which happen in other locations around the world, are scientifically termed katabatic winds.)
The Santa Ana winds are additionally funneled through narrow mountain canyons, which causes them to speed up. The hot, dry and fast nature of these winds makes them perfectly suited to spreading flames from any spark that ignites. The winds blow embers well ahead of the fire front, starting new spot fires. “Those embers are going to follow the wind and burn whatever they want,” Swain said in another video on YouTube on Tuesday.
In a couple of respects, this Santa Ana wind event isn’t a typical one: it “is especially extreme and is reaching lower elevations than usual with strong winds,” Swain said in another briefing on Wednesday morning.
The timing of the event is more in line with the norm: Santa Ana events typically happen from October through January. Part of what is raising fire risks from these events, though, is related to the influence of climate change on fluctuations in the region’s precipitation.
Fires in this area burn not in forests but in grass and brush, and the amount of that vegetation “varies widely … based on how much precipitation actually occurred prior to the growing season,” Swain explained in his video on Wednesday. The last two winter rainy seasons were extremely wet ones, so there has been an abundance of fuel. Meanwhile the latter wet winter was followed by an exceptionally hot summer, and this winter had a very warm beginning, as well as “the driest start to the winter on record,” so all of that fuel has been especially primed to ignite, he added.
With the changing climate, we expect wet periods to be wetter than in the past and dry and hot ones to be drier and hotter. This may lead to more years where substantial vegetation growth is followed by major dry spells that increasingly overlap with the Santa Anas, creating more opportunities for fast-moving, devastating fires.
In addition to the Palisades and Eaton fires, the Hurst Fire, which has burned 500 acres in the Los Angeles neighborhood of Sylmar in the San Fernando Valley, also ignited on Tuesday evening.
The direct causes of the fires are not yet clear, but there was no lightning in the area, and the majority fires in California are caused by humans, mostly accidentally.
On Tuesday Traci Park, the Los Angeles City Council member whose district includes Pacific Palisades, said the fires would likely burn hundreds of buildings, according to the New York Times. “This is going to be devastating, a devastating loss, for all of Los Angeles,” she said. Officials have reported at least two deaths and numerous injuries from the blazes.
When looking at the smoke signature of the fires on radar in his video on Wednesday, Swain noted that “this is a tremendous volume of smoke” that typically wouldn’t be seen from just brush and grass burning. “I suspect that’s likely whole neighborhoods that are on fire,” he said.
The Palisades Fire reportedly burned vegetation on the grounds of the Getty Museum in Los Angeles, “but no structures are on fire, and staff and the collection remain safe,” the museum said on its account on X (formerly Twitter). The museum will be closed through January 13. NASA’s Jet Propulsion Laboratory was closed on Wednesday because of the Eaton Fire. The facility is located in La Cañada Flintridge, Calif., which is under an evacuation order.
Though the winds are expected to slowly subside on Wednesday, the risk of fire spread is still present, Swain said. Humidity levels will drop, and temperatures will rise, so the movement of the fires will be governed more by terrain, which could change the areas that are most under threat and presents its own firefighting challenges.
