California’s wildfire activity is running below average this year. But experts warn it’s not over

A firefighter monitors flames from the Mosquito Fire in Placer County, California, in early September.
CNN  — 

Wildfire activity in California has been notably low this year, experts tell CNN, particularly compared to 2020 and 2021 when devastating wildfires erupted across the state and burned millions of acres by the time summer ended.

California has had several severe fires this year, including the Mosquito Fire, which continues to burn east of Sacramento.

However, after damp spring weather and cool temperatures delayed the onset of peak fire activity, the state’s overall wildfire activity has been “surprisingly benign,” said Craig Clements, director of San Jose State University’s Fire Weather Lab.

“But we’re not out of the woods yet,” Clements told CNN. Hot and dry offshore winds, often referred to as the Diablo or Santa Ana winds, can trigger an enormous wildfire threat, and the wind phenomena do not tend to start until the fall and winter.

“If we get those big offshore wind events in Southern California like the Santa Anas, the Diablo winds in Northern California, those could lead to bigger fires,” he said.

According to Cal Fire Battalion Chief Jon Heggie, wildfires have burned around 365,000 acres so far this year in California, which is well below the year-to-date acreage burned in recent years. In 2021, more than 2.5 million acres had burned through August, while 4.3 million acres had burned in 2020.

Heggie called this year’s burned acreage a “dramatic” drop from previous years.

Yet California remains in a multiyear megadrought which has drained water supplies and primed the vegetation for landscape-altering wildfires. Drought conditions are present in 99% of the state, according to the US Drought Monitor; conditions scientists say are part of the reason California has seen an uptick in fire activity in recent years.

Clements pointed to three things contributing to this year’s below-average fire activity: luck, firefighting strategies and day-to-day weather.

Spring brought favorable weather with cooler temperatures and some precipitation, but summer brought hotter and drier weather. California saw one of its worst September heat waves on record earlier this month, which stoked the state’s current active fires, including the Mosquito Fire which has burned more than 76,000 acres and has become the largest in the state so far this year, according to CalFire.

“While climate change has its fingerprints all over these larger fires, it’s day-to-day weather that drives fire behavior,” he said.

Daniel Swain, a climate scientist at the University of California in Los Angeles, noted although less acreage has burned so far this year, individual wildfires have been quite deadly and destructive. This year’s fires have killed nine people and destroyed more than 800 structures, according to Cal Fire.

“When people talk about this, they’re often talking about the acreage burned and actually not only does it not tell the whole story, but it arguably doesn’t tell most of what’s important about why we care about wildfires in a societal context,” Swain told CNN. “Just because the acreage burned has been less than in recent years, the impacts of these fires have actually still been really high.”

And while the acres burned are lower than the last five years, Heggie said fire conditions in California can change quickly as the seasons transition.

“It can change very rapidly in California, and so even though we are starting to think about that as a transition time, we’re still remaining ever-vigilant, and we encourage the public to do the same as well,” Heggie said.

A firefighter watches the Mosquito Fire while protecting structures on September 13.

Janice Coen, a scientist at the National Center for Atmospheric Research, told CNN despite the summer’s high heat and dry conditions, the reason there has not been a major outbreak of fires people out West would expect, is because not all conditions have been present at the same time.

“Even though there have been plenty of ignitions across the country, there hasn’t been the alignment of conditions to allow very many of them to grow large,” Coen told CNN. “It is possible that things will change. We’re heading into a period when a different type of fire is likely, so we may see more activity in Southern California than we have” so far.

Human-caused climate change has played a role in making extreme fire events worse and more likely to happen. The West’s drought and extreme heat waves laid the groundwork for dozens of major wildfires in recent years. However, just because the climate crisis is accelerating, experts say there is still year-to-year variability.

According to the National Interagency Fire Center, the potential for large fires to spark in California will remain low for the rest of the week due to above-average vegetation moisture due in part to recent rainfall, including from Hurricane Kay.

Swain said individual rain events will not erase the deeply-rooted drought, but they do help ease fire conditions in the near term.

“This is one of those weather patterns where it’s kind of boom or bust,” Swain said of the rainfall. “We get a decent amount of rain, or we probably get nothing at all, so fingers are crossed, but it’s been kind of a weird year.”