A build-up of vegetation after a few mild wildfire seasons. Recent, rainy winters that spurred more growth. The hottest July on record, drying out grasses and soil even more.
They could all combine for an especially destructive wildfire season this year.
Wildfires had a strong start in Southern California in 2024, with heat waves that brought highs of 100 degrees or more for multiple weeks and a period of monsoonal moisture that came earlier than usual at the start of July, creating even more growth.
While wildfire season typically begins in the summer months, the more destructive fires like the ones seen so far this year don’t often appear until the fall, when stronger winds help them spread.
Between the vegetation that grew but didn’t burn because of mild wildfire seasons in 2022 and 2023, and a wet winter followed by periods of excessive heat, Southern California has had far more brush for wildfires to consume, said Francesca Hopkins, an associate professor of climate change and sustainability at UC Riverside.
Prolonged heat, more common as the climate changes, also dries out plant life, making it more susceptible to burning and helping fires spread quickly.
“All of these things contributed to what was an early and severe start to wildfire season for Southern California,” said Adrienne Freeman, a spokesperson for the U.S. Forest Service.
For Hopkins, studying wildfires goes beyond an academic interest. Her home was about three miles from the path of the Hawarden fire in Riverside that burned 527 acres in July, destroying three houses and damaging four others.
“I personally feel kind of scared this year because of that confluence of fuels and high temperatures,” she said.
More acres burned
So far, the number of fires in California has stayed on pace with the state’s five-year average, but the fires have burned more acres this year, in part because of a build-up of dried grasses that allow fires to spread rapidly.
As of August 20, Cal Fire reported there have been 5,342 wildfires across the state that have burned more than 827,000 acres. At the same time last year, there were 4,494 wildfires reported in California that burned more than 124,000 acres.
Over the last five years, Cal Fire reported an average of 5,251 wildfires across the state by Aug. 20 that burned more than 530,000 acres.
In Riverside County, there have been 48 wildfires as of Aug. 15, most notably the Nixon fire, which burned more than 5,200 acres; the Eagle fire that burned around 1,700 acres and the Lisa fire that burned 890 acres, according to Cal Fire. Riverside County experienced 35 wildfires by the end of last year and eight in 2022. Riverside County numbers only include fires that were 10 acres or larger.
Other large fires this year include the Post fire that burned more than 15,500 acres in Los Angeles and Ventura counties and the Vista and Hesparia fires in San Bernardino County that burned more than 2,900 and 1,000 acres, respectively.
California had a wet winter this year, with rainfall since Oct. 1 in downtown Los Angeles at 157% of normal as of Aug. 19, 133% in Riverside, 153% in Ontario and 132% in Irvine, according to the National Weather Service.
Typically, the Santa Ana winds help spread larger fires in the later months of wildfire season, but because of the accumulation of vegetation and record-breaking heat this year, Freeman said, some wildfires have spread thousands of acres without much wind.
With the buildup of fuels, wildfires could continue through December or even into January, said Chloe Castillo, a spokesperson for the Cal Fire San Bernardino unit.
While a majority of wildfires tend to ignite from late summer through the fall, Castillo and others point out that wildfires can start anytime.
“I wouldn’t even call it a season at all,” Castillo said. “I would just consider this a fire year.”
Greater costs expected
The wildfire season is difficult to predict, Freeman said, because it’s unclear if and when a season-ending event, like significant rainfall, could hit the area.
But traditionally, as moisture levels continue to drop, August, September, and October have been the most dangerous months for wildfires.
Growing wildfires have major impacts on the environment, Hopkins said. While the annual grasses they blaze through will typically grow back each year, areas like the San Bernardino National Forest are put at risk. If affected, trees and forests could take decades to regrow, and residents would likely experience more mudslides once there’s rainfall, she said.
Fire departments are using ALERT California more, Castillo said, as the system has been expanded to 1,080 cameras and sensor arrays set up across the state as of June 2024. ALERT California uses artificial intelligence to detect and alert command centers of abnormalities in their area, like a potential fire, which can help fire crews detect fires before residents report them.
Fighting wildfires during a busy season can cost billions of dollars, said Jesse Torres, a battalion chief with Cal Fire’s Sacramento office.
This wildfire season is expected to cost more than recent ones because it’s more active and more resources are being used on each fire, including from local government partners, out-of-state assistance and Cal Fire’s aviation fleet as well as contracted aviation support, Torres said.
Crews also continue to fight the Park fire, the fourth largest fire in state history, burning nearly 430,000 acres, Torres said.
“There is a large cost associated with fighting a fire of that scale,” Torres said. “The last two years were slower in fire activity and had a very low cost in compared to the years of 2020, and 2021. These costs will continue to rise til the end of the year as we have fire activity and potential for large-scale fires with no precipitation and wind events throughout California.”
Cal Fire is introducing its first fleet of the C-130H aircraft this year and will have more in use in 2025, Torres said. The aircraft were previously acquired from the U.S. Coast Guard. And the Orange County Fire Authority has recently unveiled two Sikorsky S70 Firehawk helicopters.
What led to various wildfires this year has been under investigation, but some 90% of these fires are caused by people, said Craig Clements, a professor of meteorology at San Jose State University and director of the school’s Fire Weather Research Laboratory. The causes can include fires ignited by driving on dry grass or failing to put out campfires or cigarettes, but fires have also been caused by fireworks or power lines coming in contact with dry vegetation.
Limiting access to development and recreation in wildland areas would likely result in fewer wildfires. But, as Clements noted, “We live in California. People like to go to the mountains.”
Preventing fires often requires common sense and mindfulness, Freeman said. That could include not parking cars on dry grass, avoiding yard work with equipment that could spark a blaze or paying attention to chains that could drag on the ground and create a fire while towing a trailer.
As wildfire seasons grow longer and stronger, Hopkins said, it’s important for residents to do what they can to protect their homes.
The Hawarden fire made her realize she needed to maintain and mow part of her land where grasses grew in winter and since have died.
“The past few years were just so gentle, like we almost had no fires,” she said. “I feel like it’s easy to forget about what we should be doing as property owners to defend our property.”
The Mercury News contributed to this report.
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