Winter rains have started. Temperatures are dropping. Is California’s fire season over?
It depends where you live, experts say.
Much of the northern part of the state, generally from Interstate 80 to Oregon, has seen multiple storms in recent weeks that have soaked dry landscapes and brought snow to the Sierra Nevada. But farther south, little rain has fallen.
“Right now, the risk is really low for Northern California,” said Craig Clements, director of San Jose State State University’s Fire Weather Research Laboratory. “We are getting cold fronts coming through and bringing rain. There’s some snow, which is really helping. We are coming out of fire season. If it stops suddenly and we get warm weather, things could change. But right now it’s looking good.”
Farther south, the threat is far worse, he added.
“Southern California is still dry,” Clements said. “They are going to remain at risk, especially if there is another wind event. The Mountain Fire was a wind-driven fire. The fuels were dry. It just ripped.”
The Mountain Fire began in Ventura County on Nov. 6. A clear reminder of how October and November can often bring some of the most dangerous fires of the year to California — because six months or more have gone by without major rains — it burned 19,904 acres between the cities of Ventura and Simi Valley. Driven by 80 mph winds, it destroyed 234 buildings in the foothills around Camarillo and other communities. On Friday it was 91% contained.
Clements said that as a general rule, once an area receives at least 1 inch of rain after Oct. 1 in California, fire risk diminishes substantially. That’s because moisture levels in the soil, grasses, and other plants increase. The weather is also often cooler and more cloudy than during the hottest times of the year. If a fire does start, flames spread more slowly than during extremely dry conditions, allowing firefighters a better chance to get the blaze quickly under control.
Scott Stephens, a professor of fire science at UC Berkeley, agreed.
“If you get 1 inch of rain and it dries out for 2 weeks, there is fire potential again,” Stephens said. “If you get 1 inch over a longer time period that’s better. You are constantly adding a little bit of moisture so the things that dry out get wet again.”
Since Oct. 1, many areas across Northern California have cleared that 1-inch margin. Crescent City, near the Oregon border, has seen 8.15 inches of precipitation in the past 6 weeks, according to the National Weather Service. Eureka 6.2 inches; Redding 1.92 inches; South Lake Tahoe 1.11 inches; and Santa Rosa 1.61 inches.
But other places, including much of the Bay Area, are below that threshold. San Francisco has had 0.56 inches since Oct. 1, about the same as Oakland, with 0.55. San Jose has had less, 0.34 — all of it in one Veteran’s Day storm on Monday. More rain is forecast for next weekend.
To the south, the rain totals are microscopic. Santa Barbara has received just 0.01 inches since Oct. 1, while Los Angeles and San Diego are nearly as dry, with 0.07 inches each.
“The threat’s not gone yet,” said Cal Fire Capt. Issac Sanchez. “In many parts of the state it has certainly diminished, but in many parts of the state it hasn’t. We’re not letting our guard down. And we don’t want the public to either.”
Sanchez said that none of the Cal Fire units around California have reduced their staffing yet to winter levels, when there are fewer seasonal employees on duty.
“As soon as we feel it’s safe we’ll do it,” he said.
Overall, this fire season in California began with ferocity. Multiple large grass fires spread quickly amid high winds. On June 1, the Corral Fire, between Livermore and Tracy, burned 14,168 acres. A week later, the Post Fire in Los Angeles County burned 15,563 acres. But both were in rural areas and did little damage.
Since then, wildfire activity has been fairly modest.
As of Friday, 1.04 million acres had burned statewide — 19% less than the 5-year average for this time of year of 1.284 million acres.
One fire accounted for 41% of all the acres burned statewide. That fire, the Park Fire, began July 24 at a park in Chico when a man pushed a burning car down a grassy ravine in 100-degree temperatures. The fire burned for 64 days, blackening 429,603 acres in Butte and Tehama counties, and destroying 709 homes and other structures.
There are multiple reasons why California has so far had a relatively modest fire season, experts say. Chief among them: the state enjoyed another wet winter. Two years ago, massive atmospheric river storms broke California’s three-year drought, filled reservoirs, caused flooding, and left the Sierra Nevada with its biggest snowpack in 40 years. As a result, 2023 was a very low fire year, with just 308,958 acres burned — a drop of more than 80% from the prior year.
This past winter wasn’t as wet, but was better-than-average. On April 1, the Sierra snowpack was 113% of normal.
“We had a wet winter,” Clements said. “We weren’t in a drought. Severe drought years helped drive the big fire years we’ve had, like 2020.”
There are other factors. California did not experience large amounts of dry lightning during the summer. Gov. Gavin Newsom has boosted CalFire funding, purchasing Sikorsky Blackhawk helicopters, which can carry 1,000 gallons of water, nearly three times as much as the aging 1970s-era Huey helicopters they are replacing, and can fly at night.
The state has also helped create a network of more than 1,000 automated hilltop video cameras to detect fires early.
Cal Fire and the U.S. Forest Service have made some progress with thinning and prescribed burns in forests, but much more needs to be done after decades of fire suppression has allowed too much dead wood and brush to build up, especially with climate change increasing temperatures, Stephens said.
“In general the forests of California are still in terrible condition,” he said. “That’s just a fact. We need to do better on the fundamentals.”