This year has been the deadliest and most destructive on record for wildfires in California. Thirty-five people have died and some 8,500 structures have been destroyed, according to statistics kept by Cal Fire.
That includes at least 150 buildings destroyed in the Thomas Fire that’s burning in Ventura County. Unusually strong Santa Ana winds are fueling that fire, as they’ve fueled most of the devastating fires this year.
“What really makes big years in terms of acres burned is essentially how many really windy days we have,” said Bill Stewart, a forestry specialist at UC Berkeley.
Last year’s wet winter, which led to increased vegetation, and this year's record-breaking heat waves aren’t as indicative of fire danger as Santa Ana winds, known in Northern California as Diablo winds, Stewart said.
“It’s always dry. There’s always fuel,” he said. But wind makes fires spread fast, which makes them extremely dangerous.
“They’re much scarier in terms of planning evacuations and getting out of the way."
|California's 10 most destructive wildfires|
|Tunnel - Oakland Hills||October 1991||Alameda||2,900|
|Cedar||October 2003||San Diego||2,820|
|Valley||September 2015||Lake, Napa and Sonoma||1,955|
|Witch||October 2007||San Diego||1,650|
|Old||October 2003||San Bernardino||1,003|
|Butte||September 2015||Amador and Calaveras||921|
|Atlas||October 2017||Napa and Solano||781|
Source: Cal Fire
A 2015 study led by UC scientists found that Santa Ana-driven fires spread three times faster than other wildfires in California, and they’re responsible for about 80 percent of fire-related economic losses.
This week’s Santa Anas blowing through Southern California are some of the most severe in recent years, said Jayme Laber, a hydrologist with the National Weather Service.
“It’s probably been since 2012 since we’ve had wind this strong in the area,” he said.
The high wind is expected to last at least four days — the longest duration observed since 2007, Laber said.
Much of California’s population lives in the path of the seasonal Santa Ana winds, which start inland and blow toward the sea.
UCLA geographer Glen MacDonald said it’s especially hard to fight fires in Santa Ana conditions.
“You can’t use a lot of air resource, which we’ve really come to depend more and more on,” he said. It can be too windy or too smoky to send helicopters and planes up in the air. And even if they can be deployed, wind can make it extra difficult to target a drop of fire retardant or water.
|California's deadliest wildfires||Date||County||Deaths|
|Griffith Park||October 1933||Los Angeles||29|
|Tunnel - Oakland Hills||October 1991||Alameda||25|
|Tubbs||October 2017||Napa and Sonoma||22|
|Cedar||October 2003||San Diego||15|
|Loop||November 1966||Los Angeles||12|
|Hauser Creek||October 1943||San Diego||11|
|Inaja||November 1956||San Diego||11|
|Iron Alps Complex||August 2008||Trinity||10|
|Redwood Valley||October 2017||Mendocino||9|
Source: Cal Fire
Scientists aren’t yet sure how climate change is affecting Santa Ana winds, but many do expect more fires and a longer fire season in the future.
Given that, Stewart said we should focus more on preventing fires from becoming devastating infernos.
"We spend billions of dollars trying to use essentially quasi-military approaches to fighting fires,” he said. “It’s probably much more cost-effective to actually think of ways … to try to reduce or at least break up the continuous fuel beds we have out there.”
One way we might do this, he said, is by encouraging animal grazing near urban areas to thin vegetation. Prescribed burns and weeding are other tools.