A National Weather Service warning predicted erratic winds and low humidity in the area, which threatened to complicate firefighters' efforts to contain one of the longest-burning wildfires in state history.
The fire has been burning since Labor Day and has flared several times, sometimes covering thousands of acres in hours. It was started by someone burning debris.
"It's frustrating. You keep putting the fire to bed and it gets up and makes runs on you," said Ventura County fire Capt. Barry Parker.
The northwestern edge of the flames was moving through heavy chaparral and dense stands of pines that could fuel another run, he said.
Nearly 4,000 firefighters were working to corral the fire in Los Padres National Forest, about 70 miles north of Los Angeles. By late Wednesday, it was 41 percent contained after chewing through more than 159,281 acres, or nearly 249 square miles, of wilderness.
"The bad news is it's getting bigger. The good news, it's come out of the wilderness," Eric Brue of the California Department of Forestry told CBS News correspondent Vince Gonzales.
"We have drawn a line in the sand and we're holding it," Brue said.
On Wednesday, flames crept within a half-mile of Lockwood Valley and other mountain communities.
Firefighters spent the day clearing brush near houses and positioned equipment and hoses to fight the slow-moving flames. Elsewhere, hand crews aided by water-dropping aircraft cut fire lines around the flames.
The blaze has destroyed two barns, three trailers, a cabin and five vehicles, but firefighters were able to save 40 homes, an animal refuge and a Boys Scout camp, said Dee Bechert, a U.S. Forest Service spokeswoman.
"It was a good day, the lines held for the most part in the Lockwood Valley area, but we're still nervous about the red flag warning" for extreme fire conditions in the area, she said.
Residents of Lockwood Valley, Pine Mountain Club, Pinon Pines, Cuddy Valley, Camp Scheidek and Lake of the Woods were urged to evacuate, but many chose to stay. The community of Frazier Park was under a lower-level alert.
Firefighting costs have topped $53 million, officials said. The Federal Emergency Management Agency has authorized the use of federal funds to cover some expenses.
On Tuesday, wind-tossed embers started swift-moving grass fires near homes, Gonzales reports.
"It was a monster, it was alive," said Dale King.
King said a wall of flame nearly surrounded him. Then, he saw the fire tornados.
"At that point I thought it was the end of the world," King said. "I thought it was going to lift, jump, pick up the house, catch us all on fire and that's it."
But firefighters held the flames back.
In Lockwood Valley, Kelli Herring remained with her horse, three dogs, seven alpacas and a desert tortoise. Firefighters guarded her house. Herring, 49, said she had no intention of leaving.
"What safer place to be than with a bunch of firefighters?" she said.