The Park fire, which started on July 24 near Chico, Calif., quadrupled in size within just a few days. It now covers an area more than 12 times the size of San Francisco and is the sixth-largest blaze in California history.
The fire has destroyed at least 165 structures, with 4,200 more threatened, Cal Fire said on Monday evening. Thousands of people are under evacuation orders.
Extreme heat in June and July was the most likely cause of the fire’s rapid growth, said Park Williams, a professor of geography at the University of California, Los Angeles. “It’s the record-breaking hot and dry weather that’s singed the fuels and made them as ready to burn as they could possibly be,” Dr. Williams said.
Heat has been breaking records all summer, and Dr. Williams said records will probably continue to fall over the next several years as the burning of fossil fuels continues to add greenhouse gases to the atmosphere.
July 22, two days before the fire began, was Earth’s hottest day on record. June was the 13th consecutive month to break a global heat record. Some areas burned by the Park fire saw their single-hottest 30-day periods on record just before the blaze broke out.
Dr. Williams compared the dry conditions to those preceding California’s second-largest wildfire, the 2021 Dixie fire, which began during a drought and burned almost one million acres. The state has since emerged from drought, which makes the heat’s effect on fuels even more notable, he said.