The fire in northern Los Angeles County grew to more than eight and a half square miles, darkening skies with smoke that spread across the city and suburbs, reducing the sun to an orange disc at times.
The South Coast Air Quality Management District warned that air would reach unhealthy levels.
The fire erupted Friday afternoon in the Sand Canyon area near State Route 14 as the region was gripped by high heat and very low humidity.
About 300 homes were under mandatory or voluntary evacuations, but none had burned.
Hundreds of county and Angeles National Forest firefighters battled the blaze, aided by three dozen water-dropping helicopters and retardant-dropping planes.
“It just continues to move. It’s not slowing down,” county fire inspector Joey Marron said late Friday.
“I got all my tenants out of the recreational vehicle park and for the people that weren’t there and still have dogs, I broke into their trailers and got their dogs out,” Kurtis Bell, manager of River’s End RV Park, told KCAL-TV.
Metrolink train service in the area was halted Friday and on Saturday was subject to delays.
About 300 miles up the coast, California Department of Forestry and Fire Protection firefighters battled a nearly three-square-mile blaze in rugged mountains north of the majestic Big Sur region.
The blaze five miles south of Garrapata State Park posed a threat to 1,000 homes and the community of Palo Colorado was ordered to be evacuated, Cal Fire said. A middle school in Carmel-by-the-Sea was readied as an evacuation centre.
More than 300 firefighters were on the lines.
Highway 1 and businesses in the Big Sur area, a major summer tourist destination, remained open.