This story originally appeared News from the High Country and is part of it Climate office cooperation.
In Southern California, December wildfires are somewhat uncommon, but not entirely unusual. And this year, unseasonably desiccated conditions and robust Santa Ana winds created the perfect recipe for threatening late-season fires.
On the night of December 9 this year Franklin Fire sparkled in the hills above Malibu, breaking throughh approximately 3,000 acres in just 24 hours. By noon on December 12, the fire was less than 10 percent contained, had burned just over 4,000 acres and destroyed at least seven structures.
Last month Mountain fire erupted under similar conditions in nearby Ventura County, growing to 1,000 acres within the first hour. In two days it was over 20,000 acres; By the time firefighters brought the situation under control in early December, 240 buildings had been destroyed.
And it still hasn’t rained – neither since the fire in the mountains nor throughout the entire fall.
It is true that Santa Ana winds – desiccated winds that blow from the high desert to the coast and cause low humidity, sometimes less than 10 percent – routinely augment in the fall and winter. Less normal, however, is the lack of rainfall thrilling Currently, Southern California, although technically the region is not a state drought Already.
The weather station in downtown Los Angeles has recorded only 5.7 inches of rain fell this year, and not even a quarter of an inch fell in December, which usually falls in the middle of the region’s rainy season. In most years, there had been three or more moist days by then, which was enough to reduce the risk of fires; about 90 percent of the rainfall in the region comes from October to the end of April.
“We are still waiting for the rainy season to arrive in this part of the state, which will significantly wet the fuels and reduce the threat of large wildfires,” he said. John Abatzoglouprofessor of climatology at the University of California, Merced.
In wetter years, the windy season creates less fire risk. But now, “when ignitions and wind collide,” as Abatzoglou puts it, the landscape is primed for fire. Parched grass and bushes are ready to be burned, a fire hazard the Los Angeles County Fire Department’s forecast for December 11, the day the fire increased significantly, was high to very high throughout the Los Angeles Basin, the Santa Monica Mountains and the Santa Clarita Valley. “It hasn’t rained yet in Southern California this season,” he said Daniel Swainclimate scientist at UCLA. “This is the key. This is a real kicker.”
Robust winds coinciding with desiccated vegetation are not just a problem for Southern California. Parched conditions augment the risk of wildfires across the country – during East Coastfor example, spring and fall fire seasons. Winter fires have broken out elsewhere in the West: Colorado is spreading rapidly Marshall Fire broke out on December 30, 2021, growing from a tiny grass fire to a suburban fire that burned over 1,000 homes in just an hour.