The Charlie Fire north of Castaic grew to 3,380 acres of charred brush Sunday, as 20 to 30 homes along San Francisquito Canyon Road remained evacuated.
At sunrise, Cal Fire officials said it remained at 10 percent contained.
Firefighters made progress fighting the blaze overnight, as temperatures dropped and humidity rose.
The fire broke out on Charlie Canyon Road at 2:40 p.m. Saturday, according to Los Angeles County Fire Department Inspector Joey Marron.
The fire had scorched a few acres at the top of a ridge but was spreading, as the first firefighters arrived at 2:44 p.m. Saturday, Marron said.
They quickly called for a third-alarm response of 120 firefighters, aided by three water-dropping helicopters and two Super Scooper tank airplanes, he said.
The fire was burning in rough chaparral and scattered trees, east of Castaic Lake and north of Santa Clarita. On Sunday, it shot up a huge pyrocumulus cloud visible from as far away as LAX, as the fire generated smoke and heat that condensed into a white cloud above the blaze.
Lake Hughes Road remained closed from the boat launch ramps east of Lake Castaic, east to Dry Gulch Road. Limiting recreational boating was allowed on the eastern part of the lake, while the western part of the water body was off limits so that aircraft could scoop up water.
Francisquito Canyon Road remained closed between Low Ridge Place, near Saugus, to L.A. Fire Camp 14, near Green Valley.
At one point, about 100 homes were threatened and 20 to 30 homes along Francisquito Canyon Road were ordered evacuated.
The Castaic Sports Complex, 31230 Castaic Road, was designated as the evacuation center.
No structures were damaged and no injuries were reported, officials said.
No overall estimate of the number of firefighters was immediately available, but the City of Los Angeles had sent a strike team of 22 L.A. city firefighters was on scene along with a helicopter, spokesman Brian Humphrey said.