The dwellings, in Anaheim and the city of Orange bordering Cleveland National Forest, were protected by fire crews and there were no reports of damage by midafternoon, said Orange County Fire Authority spokesman Dennis Shell.
Pungent smoke stained the skies brown for miles across the Los Angeles metropolitan region.
"The ash was coming down like snow, I had all the windows and door shut because it was just overwhelming," said Kathie Scott, who was told by a firefighter to evacuate her Mayberry Ranch home. She got out with two dogs but had to leave behind a cat and two guinea pigs.
Red flag warnings for critical fire danger were posted for much of the region, from Santa Barbara County south to the U.S.-Mexico border.
Flames burned on rugged land east of the Orange County homes and State Route 241, which firefighters hoped would act as a firebreak. Spot fires occurred beyond the tollway, but were kept small.
"We don't want it to get across there. If it does it's within a half a mile of homes," said Stephen Miller, another county fire spokesman.
Hundreds of firefighters were brought in, along with aircraft to make retardant and water drops. Gusts of dry wind hit 60 mph in the morning, with sustained winds of about 30 mph, but they moderated in the afternoon, Miller said.
The cause of the fire had not been determined.
The Santa Ana winds, which reduce humidity and dry out vegetation, have often played a role in disastrous wildfires. In 2003, wind-driven wildfires destroyed more than 3,600 homes and killed 22 people in Southern California.