Rain will be the antidote to the worst of this California fire season.
Most years, some rains would have already arrived. But California’s grasses, woodlands, and forests remain profoundly parched — with some areas even matching or exceeding records for dryness after record-breaking summer heat and persistently dry autumn winds.
While rains won’t completely stomp out California’s fires, it will significantly reduce the likelihood of vast areas of land continuing to catch fire. This year’s sustained dryness, however, is a foreshadowing of future parched, rainless falls.
“It’s been pretty bleak this year,” Paul Ullrich, a climate scientist at the University of California, Davis, said in an interview.
There’s no immediate rainfall on the horizon this week that might douse the expansive flames of either the deadly Camp or Woolsey fires, according to the National Oceanic and Atmospheric Administration (NOAA). Though, some weather models show perhaps a little rain falling in Northern California next week.
But the bigger picture about dry California autumns — which means a longer, more potent fire season — is growing increasingly clear.
“What we’re seeing is a harbinger of things to come as this century progresses,” Sasha Gershunov, a research meteorologist at the Scripps Institution of Oceanography, said in an interview.
Specifically, recent research provides strong evidence that California is going to see a shorter, more concentrated rain season. That means more rain packed into December through February, but critically, less rain during the fall and spring.
“There is a big concern going forward when it comes to future fire seasons in California,” said Ullrich.
During the fall, the winds pick up in California, which fan the flames. This will always be a problem — it’s an ingrained and expected part of the region’s climate. But now, the winds are blowing over dryer vegetation, and the results have been historically destructive and deadly.
Making matters worse, concentrated deluges during rainy winters (like that of 2017) means vegetation will flourish after the rains, only to be dried out by drought, hotter summers, and arid falls.
“A really wet season loads the gun for the following year, giving more vegetation to burn,” Neil Berg, a climate scientist and associate director at the UCLA Center for Climate Science, said in an interview. “That is something we call whiplash.”
“Living in extremes — it’s going to become one of the pressing problems of our time,” added Berg.
There are two main drivers of California’s condensed rainy season, and accordingly, drier falls.
One is simple physics: As it grows hotter on Earth due to climate change, the atmosphere absorbs more water. So “whenever you have rainfall, you have more rainfall,” but there’s less moisture available in spring and fall, said Ullrich.
Second, the weather systems that bring storms to the Golden State — propelled by strong, higher atmospheric winds called the jet stream — are getting pushed farther north. That means more of California will be will be subjected to drier, desert-like conditions, explained Gershunov.
“We can expect a longer dry season,” Gershunov said.
Although the rains haven’t shown up much this fall, that certainly doesn’t mean the entire season will be a wash. About 12 to 15 percent of California Octobers see negligible rain, noted Ullrich. So this may be just be a dry start to an average (or above-average) rainy season.
“But it would be extremely anomalous if we had no rainfall for the next month,” Ullrich said.
When the rains do come, the only hope is that they’re normal.
Heavy rains drive terrible mud slides down burned land — and there’s now a lot of freshly burned terrain. And like anywhere, too much rain at once means flooding.
Unfortunately, with the extreme and historically unprecedented levels of carbon collecting in our atmosphere, temperatures are expected to continue rising this century.
California should expect less rain in the fall, more land torched by fire, but more deluges during the winter.
“The rains are usually so welcome, but not in their extreme form,” said Berg.