Tuesday, Santa Claus Ana’s winds swept across Southern California, scattering embers and then fanning the flames of a growing wildfire. At night, residents received urgent text alerts warning of potential 100 mph gusts – a terrifying escalation that turned a precarious situation into a full-blown crisis. As winds howled, new embers took flight, igniting new fires in dry, brittle brush that hadn’t seen significant rain in more than eight months.
Los Angeles County, facing drought-like conditions, was a powder keg waiting for a spark. Firefighters battled winds so strong that planes used to drop water and fire retardants were grounded. Authorities warned in a news release Wednesday morning that “all residents of Los Angeles County are at risk.” Evacuation orders have since displaced tens of thousands of residents, and thousands more are awaiting updates. As of Wednesday evening, three major fires had consumed more than 13,000 acres with containment efforts lagging: the Palisades Fire in Pacific Palisades and Malibu, the Hurst Fire in Sylmar, and the Eaton Fire near Pasadena have shown no signs of slowing down, as of this writing. 0 percent contained, and have already become the most destructive in California history.
The fires became catastrophic so quickly due to unusually dry and windy conditions: “The slightest spark, whether from a lightning bolt, a person or a campfire, will quickly intensify,” says Jennifer Marlon, a research scientist and lecturer at Yale University. Yale School of the Environment and Program on Climate Change Communication. “Once a fire starts under these conditions, it’s very, very difficult to get it under control,” adds Kaitlyn Trudeau, senior research associate in climate science at the nonprofit news organization Climate Central.
Santa Ana wind events are not uncommon. “We see it every year around this time,” says Jason Moreland, senior meteorologist at emergency communications platform AlertMedia. These descending winds, which come from inland, are caused by a dry high pressure system coming from the northwest and a humid low pressure system coming from the south. “It’s like you have a garden hose and you bend it in half to shut off the water. If you make a hole in the side, you have a lot of pressure to get out,” Trudeau explains. “That’s basically what’s happening with the air.”
However, these winds are much stronger than usual due to a drop in the jet stream near the Baja Peninsula in northwest Mexico, Moreland says. Winds that are usually relegated to higher altitudes reach lower areas of terrain. “Every decade we face wind events of this magnitude,” he says.
Although this wind event seems extreme, Noah Diffenbaugh, professor and principal investigator at Stanford University Woods Institute for the Environmentexplained that this could simply be due to natural weather variability and that more research is needed to find out if this is due to climate change.
However, while the winds are not unusual for the season, climate change increases the risk late or early season wildfires in California. “This is not only a particularly strong wind event, but also a particularly dry season here in early January,” says Diffenbaugh. Southern California’s rainy season, which runs from October to April, saw record rainfall, following one of the driest falls on record. As precipitation is more variable due to climate changethe overlap between the windy season and the dry season is increasing. “We’re seeing a lot more hot, dry, windy days, especially in Southern California,” Trudeau says.
