Summer officially ends next week, but California’s devastating wildfire season will almost certainly rage on.
As of Monday, three enormous blazes — the Valley Fire in Lake, Napa and Sonoma counties; the Rough Fire in the Sierra National Forest in Fresno County; and the Butte Fire, burning in Amador and Calaveras counties — had already charred 270,000 acres, an area 10 times the size of the city of San Francisco.
Experts said at least another month, possibly two, of extreme fire risk remains before hoped-for El Niño winter rains could begin to dampen dry grasses, shrubs and trees all over California.
And, if history is any indication, the most destructive fires can come in October, when conditions are their driest. Major infernos like the 1991 Oakland Hills Fire, which killed 25 people and destroyed 2,843 homes, and the 2003 Cedar Fire and the 2007 Witch Fire, which together burned nearly 3,500 homes in San Diego County, all began in October.
Making fire risk even higher now, moisture levels in trees and brush are at record lows after four years of drought.
“Until we get rain, it’s not going to get any better,” said Scott Stephens, a professor of fire science at UC Berkeley.
Through Monday, 738,516 acres had burned in California in 2015, a 75 percent increase from the same date last year, and a 37 percent increase when compared to the five-year average.
Perhaps even more sobering, the drought already has killed an estimated 12.5 million trees in California’s forests, according to the U.S. Forest Service, from ponderosa pines in the Sierra to oaks in the valleys and coastal hills. And those trees are providing mountains of tinder that will be around for years.
“I will retire in nine years, and this drought will affect the rest of my career,” said Jim Crawford, division chief for the Cal Fire Santa Clara Unit in Morgan Hill.
“The stuff that’s died over the last three or four years will be fuel for wildfires for the next 50 years, even if we have epic rains this winter,” said Crawford, whose unit fights fires in Alameda, Santa Clara, Contra Costa and parts of Stanislaus and San Joaquin counties.
Crawford said that soil moisture levels are so low that many plants and trees are barely surviving.
“There’s less water for them to take in,” he said. “They are not actively growing. They are more susceptible to disease and to burn.”
People in rural areas need to cut brush and trees away from their homes now if they haven’t already and be prepared to evacuate quickly if a fire starts near them, he added. In the long term, he said, state firefighters need more engines and firefighters to knock down big fires early, and more resources to expand public education and enforce brush clearing around homes.
Meanwhile, the steadily warming climate is playing a larger role.
Last year was the warmest year ever recorded in the world since 1880, when modern temperature measurements were first kept, according to NASA and the National Oceanic and Atmospheric Administration. Already, 2015 is on pace to break that record again.
A new scientific study published Monday found that the Sierra Nevada snowpack, which historically has provided 30 percent of California’s water supply, is at the lowest level in 500 years.
“We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures,” said Valerie Trouet, an associate professor of dendrochronology at the University of Arizona, who helped write the study, which was published online in the journal Nature Climate Change.
By April, the Sierra Nevada snowpack was at 5 percent of normal. The area received such little rain and snow that much of it quickly melted with especially warm weather this winter — like the 70-degree days that defined January.
Gov. Jerry Brown made a similar point during a news conference Monday. He noted that the current extreme fire conditions are not just a once-in-a-lifetime event. Although California has had droughts before, climate change is making them worse, and the state should prepare for more fires, even refugees from Mexico and Central America fleeing climate-caused droughts and disasters, he said, in the decades to come. “This is not just this year. This is the future from now on,” he said. “It’s going to get worse, just by the nature of how the climate is changing.”
On Monday, 11,000 firefighters around California battled at least a dozen major fires.
The Valley Fire had burned 62,000 acres by Monday evening and destroyed more than 400 homes and 400 other buildings, making it one of the worst in state history. It was just 10 percent contained. The Rough Fire was 40 percent contained and had burned 139,133 acres. And the Butte Fire had burned 71,523 acres and was 35 percent contained.
Residents in fire-prone regions around the Bay Area said the fires around the state are a wake-up call.
“I get nervous in September and October every year. With the drought I’m very concerned,” said Susan Piper, whose house burned down in the 1991 Oakland Hills Fire.
“Our trees are really suffering this year,” she said. “If you look along Highway 13, you see so many dead pine trees. The eucalyptus in the hills are very stressed. So when we hear about the conditions in Lake County, we are facing the same thing here. It’s parched. It could go very quickly.”
Piper advised people in risky areas to photograph and video their possessions and post the images “in the cloud” online. She urged residents to cut back brush, keep up their fire insurance and create family disaster plans.
“Like a good Boy Scout, you must always be prepared,” said Piper, who remembers driving the wrong way down Hiller Drive with her children in the car to escape as trees burned around her. “We live in harm’s way. I’ve gotten religion since the fire.”
Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN.