The secret to Los Angeles fires: heavy rainfall. Unprecedented popularity. Unusual wind.
One fire appears to have been started by a spark from an old electrical wire, and another was allegedly started by an Uber driver obsessed with flames.
Ultimately, the Eaton and Palisades fires destroyed more than 16,000 homes, businesses and other structures and killed 31 people. They are the second and third most destructive wildfires in California history, behind the 2018 Camp Fire that leveled the town of Paradise, destroying more than 18,000 structures and killing at least 85 people.
All three fires — and many others that have struck California in recent decades — have a key common factor: global warming, which many scientists say is making California’s always dangerous fire season more worrisome than ever.
California is suffering from bigger fires as climate change intensifies. Most of the state’s most destructive, deadliest and largest fires have occurred in the past quarter-century.
A study published in 2023 said California summer forest fires burned five times the area between 1996 and 2021 than during the previous 25-year period.
“Climate change is leading to increased fire activity,” said John Abatzoglou, a co-author of the study and a professor of climatology at the University of California, Merced.
Climate change increases the hazards of other man-made factors that often trigger large-scale fires. The Jan. 7 fire was not only about alleged arson and aging electrical infrastructure, but also about the way firefighters and officials made decisions before and during the fires, as well as the impact of fire-prone wildlands and inadequate escape routes.
Record heat dries out Southern California
The prelude to the most destructive fires in Southern California history was the hottest summer on Earth, and the hottest July in California history.
In fact, summers are warming to unprecedented levels, both in California and globally.
Last July, before the Eaton and Palisades fires, California and the West were in turmoil. Palm Springs had its hottest day on record, with temperatures reaching 124 degrees; so did Las Vegas (120 degrees); Reading (119); Barstow (118); and Palmdale (115). The temperature in Lancaster also reached 115 degrees, tying the record high temperature.
Globally, 2024 was also a year on record—the entire year was Earth’s hottest on record, worse than any year in NOAA records since 1850.
All that heat is having a worrying impact on California’s wildfire risk by sucking moisture out of vegetation, according to a blog post by UCLA scientists about the climate and weather factors driving recent wildfires.
The summer and fall of 2024 were the hottest along the Southern California coast since at least 1895, and the high temperatures in the summer of 2024 “appear to be partially responsible for the sharp decline in dead fuel moisture during the summer,” the scientists wrote.
feast or famine rain
Another expected effect of climate change is the increase in severe weather whiplash from dry to wet and wet to dry that California faces. Another study published in the journal Nature Reviews in January found that more “hydroclimate whiplash” events are expected around the world due to human-caused global warming.
“Hydroclimate whiplash is already increasing due to global warming, and further warming will bring even greater increases,” climate scientist Daniel Swain, the study’s lead author, said in January. “California’s whiplash sequence triples fire risk: first, a large increase in the growth of flammable grasses and shrubs in the months leading up to fire season, and then to unusually high levels of dryness as the extreme dryness and warmth follow.”
A flood-to-drought pattern worsened vegetation conditions, leading to January’s fires.
California went from its driest three-year period on record from 2020 to 2022 to a series of wet years. By mid-2024, the region will be one of the greenest since 2000, according to a blog post by UCLA scientists.
Subsequently, large swaths of Southern California were plunged into a record drought during the water year that began on October 1, 2024, with almost no rainfall in the months leading up to the January 2025 fires.
Before the January fires, the last significant rainfall in downtown Los Angeles was on May 5, when a tenth of an inch fell. From October 1, 2024 (the beginning of the water year) to January 15, only 0.16 inches of rain fell, just 3% of the average rainfall of 5.56 inches for the city center at that time.
The city center hasn’t been this dry in about sixty years. The only recorded drier period was from October 1, 1903, to January 15, 1904, when only a trace of rain accumulated in the city center.
Areas with the driest 3.5 months on record include Los Angeles International Airport, UCLA, Van Nuys, Woodland Hills, San Diego, Lancaster and Camarillo.
Neil Lareau, an associate professor of atmospheric sciences at the University of Nevada, Reno, said that due to the “severe lack of precipitation across Southern California,” “not only is the already dry fuel drying out, but the moisture content of the fuel at the site is very low, so it just supports very rapid fire spread.”
Almost unprecedented Santa Ana style
Another key factor in the fire’s damage was Santa Ana’s strong winds. There is no evidence that the increase in Santa Ana winds is attributable to climate change.
But they make an already dangerous situation even more dire. Santa Ana’s extreme winds spread rapidly, with the worst fires occurring just upwind of densely populated areas.
“In this case, you’ve got a trifecta,” said Michael Lord, a former battalion chief with the Orange County Fire Department and now an emergency management consultant.
He said earlier this year that the fires were spread by “super strong winds – twice as strong as a normal Santa Ana – they blew down the mountains and turned into urban fires, and their burning characteristics have a lot of similarities to the Dresden fire bombs of World War II.”
Urban fires, which spread from house to house through the explosion of millions of embers, are “more severe than normal wildland-urban interface fires,” Lord said. “So we’ve suffered a huge loss.”
The winds of January 6 and 7 were not a typical Santa Ana event. The storm was unusual, producing gusts of up to 100 mph, “as extreme as we’re going to see,” said Ryan Kittell, a meteorologist with the National Weather Service. “We haven’t seen winds like this since the 2011 storm that devastated the Pasadena area.”
These gusts are the product of mountain wave wind conditions, meaning they are oriented quickly down the slopes of the San Gabriel Mountains, creating strong and dangerous outbursts. Milder Santa Ana winds often flow through canyons but are not strong enough to climb mountains.
This latest storm brought gusty winds from the north to the northeast; in a typical Santa Ana wind event, winds blow from the east to the northeast, weather service meteorologist Ross Schoenfeld said.
In other words, they struck areas that would not normally be attacked by the Santa Ana, such as Altadena and Pacific Palisades.
