Which parts of California face the highest risk?
California is beginning to feel the impacts of the unusually dry weather it had this winter, and that doesn’t bode well for wildfires.
After a modest fire season last year, scientists say the lack of rain in February and March, combined with hot weather last month, has left vegetation in Northern California drier now than it has been in any July since the state’s historic five-year drought from 2012 to 2016. Rainfall was half of average in the Bay Area this winter but 100% of normal in much of Southern California — a rare occurrence where for the first time in 15 years, Los Angeles received more precipitation than San Francisco.
The result: Fire experts are predicting high fire risk over the next four or five months, particularly in Northern California — a danger made more challenging amid the coronavirus pandemic.
“We are now at the point of turning the corner. We are in peak fire season,” said CalFire Chief Thom Porter on Thursday. “That means the fires aren’t just going to go out as the sun goes down. They are going to start burning through the night, burning into the chaparral and the forests. This is the time of year when fires start to get bigger and more difficult to control.”
Fire crews Thursday nearly had finished putting out the 5,400-acre Crews Fire, a blaze that began Sunday in rural range lands east of Gilroy. It destroyed one house, caused dozens of people to be evacuated and required more than 800 firefighters to battle.
Highlighting the dramatic difference between Northern and Southern California, 46% of California’s
land area — nearly all north of Fresno — is currently experiencing at least moderate drought conditions, and 20% has severe drought conditions, according to the U.S. Drought Monitor, a weekly federal report.
Particularly dry are communities north of Alameda County, including Napa, Sonoma, Mendocino and Lake counties — where devastating fires in 2017 killed dozens of people.
“It was a dry year,” said Jan Null, a meteorologist with Golden Gate Weather Services in Half Moon Bay. “That’s not a good jumping off point as we go into the rest of the summer and the fall.”
Although fire officials sometimes say every year that they expect a bad fire summer — a tactic that can keep the public alert but also increase chances for more state funding — historically, records show that most of California’s worst fire seasons, ranked by acres burned, come after dry winters, not wet winters.
That’s because more snow falls in the Sierra Nevada in wet winters. The longer it lasts into the summer, the less area there is to burn. This year on April 1, the statewide Sierra snowpack was just 54% of its historical average. Last year it was 161%, and California ended up with a below-average fire year.
Wet winters also increase the amount of moisture in grasses, shrubs and trees, reducing flammability when they are hit with sparks from downed power lines, lightning strikes or carelessly thrown cigarettes.
Craig Clements, director of the Fire Weather Research Laboratory at San Jose State University, said moisture levels in chamise, a common wild shrub, averaged 72% on July 1 in the hills above Los Gatos, well below the 10-year July 1 average in that location of 86%.
In general, moisture levels in Bay Area plants now are where they were last August and at levels not seen in July since 2014 and 2015, during the peak of the state’s historic drought.
“The soil is drier than normal,” he said. “So the plants are going dormant — shutting down — earlier than normal. Who knows how this is going to play out in August? But right now, this is way low.”
On top of that, temperatures in June were hotter across Northern California. In San Jose they were 2.2 degrees Fahrenheit above normal, with an average daytime high of 82.8 degrees, Null noted.
In November 2018, a fire caused by fallen PG&E power lines in Butte County roared through the town of Paradise, killing 85 people in the worst fire disaster in state history. A year earlier, the Wine Country fires killed 31 people and destroyed more than 6,000 homes across Napa, Sonoma and Lake counties.
California has beefed up firefighting capabilities this year. The state is spending $285 million to buy 12 new Blackhawk helicopters, which can carry 1,000 gallons of water, nearly three times as much as the aging Huey helicopters they are replacing.
The state also hired 172 new CalFire staff members and is spending $135 million on upgraded communications equipment and 108 high-definition cameras to detect fires early.
Coronavirus makes everything more difficult, however. Firefighters will be given briefings by radio rather than in person. They will eat in shifts and sleep farther apart.