The Pawnee Fire, fanned by dry, erratic winds, roared across the hilly eastern backbone of Lake County, destroying 12 structures (10 of them homes) and threatening some 700 others.
The fire surged from 450 acres after it started Saturday night to 3,000 acres by Sunday afternoon, forcing the evacuation of the Spring Valley area, a community of about 3,000 residents northeast of Clearlake near Highway 20, officials said.
"Given the weather and the changes in wind direction, the fire is moving in multiple directions," said Paul Lowenthal, assistant fire marshal for the Santa Rosa Fire Department.
These kinds of fires don't normally hit until late summer or fall, but Lowenthal said the area is drier than normal for this time of year.
"I don't think any of us thought we would be here this early in the season," Lowenthal said.
"This is the last thing anyone wants to go through.
It has the potential to get a lot bigger given the wind and the directions it's being pushed."
More than 235 firefighters battled the fire, which sent plumes of smoke thousands of feet into the air. It raged through oak-dotted hills that only a few years ago had been blackened by fire and crackled through grass so brittle that it crunched like glass underfoot.
Firefighters used bulldozers to cut a fire break and dropped water and retardant from aircraft. Residents and several fleeing deer evacuated on New Long Valley Road as flames licked atop the hillside.
The American Red Cross set up an emergency shelter at Lower Lake High School.
"Oh, look at that hill.
I bet those flames are 400 feet tall," said Leona Demits, who was pacing in front of the gate to her friend's Spring Valley home, warily watching the orange glow along the ridge behind the house. Demits and her husband, Galen, were staying in the house temporarily during a move to Redding from Fort Bragg, where they were more used to rain and fog.
"Man, I didn't know you had to spend the summer half-packed up," she said, smoking a cigarette and sweating in the 100-degree heat.
Rural Lake County has had more than its share of devastation in recent years.
It was spared by fires that ravaged neighbouring Napa and Sonoma counties last year, but the 4,000-acre Clayton Fire burned much of the town of Lower Lake in August of 2016, destroying at least 300 homes and businesses and forcing thousands to evacuate.
A year earlier, the 76,000-acre Valley Fire killed five people and destroyed more than 2,000 homes and structures in and around Middletown, including Harbin Hot Springs and Hoberg's Resort.
Fire officials said the most destructive fire in the history of Lake County was started by faulty wiring on a hot tub. Large fires also raged through the county in 1996 and 2012.
The worst wildfire in California's history brings the death total to 40 with many more missing and thousands of homes destroyed