A rapidly growing wildfire has broken out some 80km north of Los Angeles, burning 2000 hectares, while two major fires that have been burning in the metropolitan area for more than two weeks are getting under control, fire officials said.
The Hughes Fire in the Castaic Lake area of Los Angeles County forced evacuations with warnings of "immediate threat to life", while much of Southern California remained under a red-flag warning for extreme fire risk due to strong, dry winds.
According to Los Angeles County officials, some 19,000 people, roughly equal to the entire population of Castaic, were under mandatory evacuation orders, and another 16,000 were under evacuation warnings.
Los Angeles County, the state of California and the US Forest Service said their firefighters were responding. The Angeles National Forest noted its entire 280,000-ha park in the San Gabriel Mountains was closed to visitors.
The California Department of Forestry and Fire Protection (Cal Fire) said that as a result of the red-flag warning, some 1000 firefighters were deployed around Southern California in anticipation of fast-moving fires.
Video on KTLA television showed helicopters scooping water out of a lake to drop on the fire as flames spread to the water's edge.
The California Highway Patrol said Interstate 5, a major north-south highway, was closed in the area of the fires due to poor visibility.
While the new fire raged, Cal Fire said the two deadly fires that have ravaged Los Angeles came under greater control.
The Eaton Fire, which scorched 5,600 ha east of Los Angeles, was 91 per cent contained, while the larger Palisades Fire, which consumed 9,500 ha on the west side of Los Angeles, was 68 per cent contained.
Containment measures the percentage of a fire's perimeter that firefighters have under control.
Since the two fires broke out on January 7, they have burned an area nearly the size of Washington DC, killed 28 people and damaged or destroyed almost 16,000 structures, Cal Fire said. At one point, 180,000 people were under evacuation orders, according to Los Angeles County officials.
Private forecaster AccuWeather projects damage and economic losses at more than $US250 billion ($A400 billion).
In the past two weeks, a series of smaller wildfires have been extinguished or brought largely under control in Southern California.
With AAP.
