By Brian K Sullivan and Lauren Rosenthal, Bloomberg
Away from California’s coastline, the interior hillsides are a carpet of brown, dry brush and grasses.
Nearly 40% of the state is in drought, and with the state’s Santa Ana and Diablo winds set to pick up in the coming weeks, any errant spark threatens to race across a landscape ready to ignite.
RELATED: Why are they called the Diablo Winds?
“The grass levels are very thick, and the brush is very dry,” said David Acuna, spokesman and battalion chief for California Department of Forestry and Fire Protection, known as Cal Fire, comparing the state to a haystack.
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California started 2025 with tragedy on the fire front, as 31 people died in the Los Angeles area from the Eaton and Palisades fires in January. The fires were the state’s second- and third-most destructive, according to Cal Fire. In all, 6,504 fires have burned so far in 2025. Through the end of August, they consumed 425,680 acres, which is more than last year but less than the five-year average of 772,489 for the same time period.
But the worst of California’s fire season is likely ahead as the windy season nears. Powerful, sustained wind events usually begin in October and spill over into early winter. Known as Santa Anas in Southern California and Diablo or Sundowner winds in other parts of the state, they’re driven by pockets of high pressure across Nevada and Utah that push winds west toward the Pacific. The winds gain speed as they cross mountains while also becoming drier and hotter as they roll down slopes.
The other key ingredient for fires is fuel, and that’s abundant in California after several winters in a row of plentiful rainfall that’s allowed natural and invasive plants to thrive. Now, all that kindling is dry following the long, arid months of summer. Any fire “is going to grow exponentially,” Acuna said.
That may come as a surprise to people living in coastal California after a summer of unusually mild weather, said Daniel Swain, a climate scientist with the University of California system.
“It’s been a relatively cool summer in places like San Francisco and LA,” he said, but the same isn’t true for California’s mountains and foothills, where temperatures have been above-average at higher elevations.
While nature sets the stage, most fires are caused by human activities, Acuna said. Many fires are sparked by accident: A car might set off a grass fire or a power line may touch off brush. Even a person mowing their lawn on a windy day might send embers into the air. Cal Fire has been trying to drive home this message in 2025 by repeating an old adage: “One less spark causes one less wildfire.”
The state’s utilities have faced lawsuits over deadly blazes in the state linked to power equipment. In an effort to lower the risk of explosive fires and potential liability, some have implemented measures that include cutting power when winds rise. Human-caused climate change is also increasing the risk of larger, more explosive fires.
Acuna said one of the biggest lessons of 2025 has been that no one in California should think they are immune to wildfires: “Even urban areas can be wildfire-prone, so it is important to be ready to evacuate.” Residents should prepare “go bags” with clothes, medicines and important documents; know where they and their pets and livestock can shelter; and have at least two escape routes from their neighborhoods memorized.
Nationally, there have been 47,183 wildfires across the US burning nearly 4.2 million acres in 2025, which is more blazes than the 10-year average but lower than the almost 5.6 million acres usually burned to date, according to the National Interagency Fire Center. Large parts of the US Mountain West, though, will see wildfire risk decrease as colder weather sets in.
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