The days get shorter, the evenings get cooler and stores put out their Halloween displays.
But even as autumn settles in, California’s fire season hasn’t ended – not by a long shot. While some of Northern California’s deadly wildfires continued to smolder Tuesday, emergency officials in Southern California sounded the alarm about high winds, triple-digit temperatures and the threat of new fires. Red Flag warnings for high fire risk were in effect from the Mexico border to areas north of Bakersfield, according to the National Weather Service.
“California is still very much on the radar screen,” said Tim Brown of the Western Regional Climate Center, a Reno think tank.
Although the risks from new fires have abated in Northern California in recent days, officials cautioned that the perils haven’t been completely extinguished despite the light rains that swept through the area last week. Temperatures were expected to hit the mid-80s in the Sacramento area Tuesday and the mid-90s around Santa Rosa, where the Tubbs Fire killed 22 people earlier this month.
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“In two days, it’ll be as dry as it was before the rains, roughly,” said Bill Stewart, the co-director of UC Berkeley’s Center for Fire Research and Outreach.
Such long fire seasons are the norm for California – where rain is generally absent for nearly half the year. Thirteen of the 20 most devastating fires in California history, as measured by the number of buildings destroyed, have started on Oct. 1 or later, according to Cal Fire records. That includes the Tubbs Fire in Sonoma County, which burned 5,300 structures – more than any single fire ever in California. All told, this month’s fires in Northern California killed 42 people and destroyed an estimated 8,400 structures.
Why are October and November so dangerous? Mainly because a year’s worth of vegetation growth has been drying out since spring in California’s lowlands and foothills. That happens every year.
This year, however, has been exceptional. The rainiest winter in Northern California history left an extra-thick carpet of grass and brush. That was followed up by the hottest summer ever recorded in the state. The average temperature of 73.7 degrees was 3 degrees above the historical average and a half-degree hotter than the old record set in 2006, according to the Western Regional Climate Center.
Add to that the seasonal Diablo winds, which topped 60 mph, and California’s wine country was set for disaster. In the Santa Rosa area, the gusts blew hot embers from grasslands and forested areas nearly a mile into highly populated neighborhoods.
Some scientists believe climate change may have contributed to the carnage. Daniel Swain, of UCLA’s Center for Climate Science, said the hotter-than-ever summer left the grassy areas and forests more prone to ignition.
“Vegetation is absolutely drier than it would have been,” Swain said. “I don’t think it’s a coincidence that it happened (following) the same summer that was the hottest it’s ever been.” In Southern California, where the Santa Ana winds have kicked up and temperatures have topped 100 degrees, the fire risk “is about as high as it gets,” he said.
Cal Fire officials said the calendar and occasional early-autumn rains can fool Californians into believing fire season has ended. All it takes to create a catastrophe is a spark from a trailer’s loose chain dragged along a roadway, a lit cigarette or a downed power line.
“People think they can start doing their residential (back) yard burning, ‘Oh I’ve got to get rid of all this junk. I’ll just light it up,’” said Lynne Tolmachoff, a Cal Fire spokeswoman.
Brenda Belongie, a meteorologist with the U.S. Forest Service who predicts fire risks for the federal government, said California needs what scientists call a “season-ending” series of rainstorms to put the perils to bed once and for all.
“What you want is another storm after that, another storm after that and another storm after that,” Belongie said. “You want a series of storms over a period of several weeks.”
Nothing of the sort is in the forecast.