December wildfires are now a thing

This story first appeared on High Country News and is a part of Climate table cooperation.

December wildfires in Southern California are somewhat rare, but not entirely out of the norm. And this year, extremely dry conditions and strong Santa Ana winds created the perfect recipe for dangerous fires later in the year.

On the night of December 9th Franklin Fire Sparks ignited in the hills above Malibu, to tearAbout 3,000 acres in 24 hours. As of noon on Dec. 12, the fire was less than 10 percent contained, with just over 4,000 acres burned and at least destroyed. seven structures.

last month, Mountain fire It ignited in similar conditions in nearby Ventura County, growing to 1,000 hectares in the first hour. In two days it was over 20,000 acres; By early December, 240 structures had been destroyed before firefighters contained it.

And it still hasn’t rained—not since the Mountain Fire, or all fall.

It’s true that the Santa Ana winds—dry winds that blow from the high desert to the coast and sometimes bring humidity below 10 percent—regularly pick up in the fall and winter. But less normal is the absence of rain seizure Southern California currently, although the region is technically a drought yet.

There is a weather station in downtown Los Angeles recorded only 5.7 inches of rain fell this year, and not even a quarter of an inch in December, which is generally the middle of the region’s wet season. Most years would have seen three or more rainy days by this time, enough to curb the risk of some wildfires; About 90 percent of the rainfall in the region comes from October to the end of April.

“We’re still waiting for a wet season to start in this part of the state that will meaningfully soak fuels and put the major fire danger to bed,” he said. John AbatzoglouProfessor of Climatology, University of California, Merced.

In rainy years, the windy season presents less fire risk. But now, as Abatzoglou puts it, “when the flames and the wind collide,” the scene is set for fire. Dry grass and bushes are ready to burn fire hazard According to the Los Angeles County Fire Department’s December 11 forecast, the day of significant fire growth was high or very high in the Los Angeles Basin, Santa Monica Mountains and Santa Clarita Valley. “It hasn’t rained in Southern California yet this season,” he said Daniel Swainclimate scientist at UCLA. “That’s the key. That’s the real kicker.”

High winds combined with bone-dry vegetation aren’t just a problem for Southern California. Dry weather conditions increase the risk of wildfires across the country East coast‘s spring and fall fire seasons, for example. And winter fires have broken out elsewhere in the West: Colorado is moving fast Marshall fire On December 30, 2021, it went from a small grass fire to a suburban fire, burning more than 1,000 homes in just one hour.