Casey Hutchings, a fire captain for the Cal Fire unit in Fresno County, was caught in a lightning siege on Sept. 2 while looking for the ignition source of a wildfire on the outskirts of the city of Coalinga, Calif., about 60 miles southwest of Fresno.
As he scanned the area, flashes of lightning were visible over the hills in the distance, with bolts descending from the clouds and fanning out across the grassy landscape.
Then the storm got closer.
At one point, a bolt hit the ground 100 yards from his truck.
“It took my breath away,” said Captain Hutchings, who has worked as a firefighter for 23 years. “That was my first experience being that close to down strikes.”
California gets relatively little lightning compared with states in the Midwest and along the Gulf Coast where thunderstorms commonly form in hot, humid weather. Last year, California recorded 0.6 lightning strikes per square kilometer, while Florida saw 91.4, according to the weather data firm Vaisala.
California this summer has had more lightning than usual, with 79,698 lightning strikes recorded from June 1 to Aug. 31, the third-highest number for these three months since 2016, according to Vaisala. Northern California in particular recorded the most strikes compared with any other summer since 2016.
“This summer has been the year of lightning,” said Brent Wachter, a fire meteorologist with the U.S. Forest Service in Redding, Calif. “We’ve been breaking monthly records.”
The lightning has ignited hundreds of wildfires though few have grown into very destructive ones for a number of reasons, including cooler, wetter weather and fast responses by firefighters.
Fires have burned 425,680 acres since the start of the year, compared with the five-year average of 772,489 acres for this point in the year, according to Cal Fire, the state’s firefighting agency.
Firefighting resources, including planes and helicopters, have been available to identify and extinguish blazes quickly, said Jesse Torres, a spokesman for Cal Fire.
They haven’t been sucked up by the types of gargantuan wildfires that the state has seen in recent summers, such as the Park fire, which burned through nearly a half million acres last summer.
“There were a lot of good catches this summer,” Mr. Torres said.
Thunderstorms that generate lightning are fueled by moisture, and the air in California has been laden with moisture much of the summer.
At the start of the season, an area of low pressure sat off the West Coast, channeling moist, cool air from the Pacific Ocean. In July, when moisture poured into Northern California, lightning zapped the landscape.
In late August, a shift in the prevailing wind pattern known as the monsoon, transported moisture from the Gulf into the Southwest.
On Aug. 26 alone, California recorded 12,152 “cloud-to-ground strokes,” its third-highest daily count in the past 10 years, according to Vaisala. The lightning that occurred from Aug. 23 to 28 in Northern California sparked an estimated 429 wildfires, Mr. Wachter said.
“Luckily, a lot of the storms were of the wetter variety, so we didn’t have as many large fires as one would think,” he said.
In the first week of September, another push of monsoonal moisture prompted lightning outbreaks in parts of the Central Valley, the Sierra Foothills and Southern California.
In many cases, the lightning was dry, meaning it struck outside of rainstorms.
Dozens of wildfires broke out, including the TCU September Lightning Complex fire in Calaveras, Stanislaus and Tuolumne Counties, which tore through the gold rush town of Chinese Camp.
“This was a really prolific lightning event, the kind of which we don’t see every year,” said Daniel Swain, a climate scientist at the University of California, Los Angeles.
Dr. Swain said the September lightning was concentrated over the Central Valley’s rural, flat patchwork of towns, grasslands and irrigated agricultural land.
“There are more people, there’s a good road network, and a lot of the vegetation is largely resistant to burning,” he said.
If the lightning had been focused over the state’s rugged coastal mountains blanketed in thick vegetation, more intense wildfires could have ignited.
Those mountains were hit with dry lightning and strong winds during storms in 2020, when hundreds of fires ignited, including the August Complex fire, the state’s largest ever at 1 million acres. That year, 4.2 million acres burned in the state.
There is concern that lightning could become more common in a changing climate with a warmer atmosphere that can hold more moisture.
This is why scientists at the University of California, Merced, used machine-learning models trained on weather data to predict lightning patterns in the wildfire-prone West in the future.
Their study, published in the journal Earth’s Future in August, reported that from 2031 to 2060, the Sierra Nevada, where California most commonly gets lightning, could see an estimated four additional days of lightning striking the ground per year on average.
Amy Graff is a Times reporter covering weather, wildfires and earthquakes.
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