LOS ANGELES (Reuters) - A California wildfire that started on Monday at a campground in the foothills above Santa Barbara grew to 1,800 acres on Tuesday, but some 50 homes that had been threatened by the flames were no longer in danger, officials said.

The so-called White Fire, named after the White Rock Day Use camping area in the Los Padres National Forest where it flared up Monday afternoon, forced more than 4,000 campers and day use visitors to evacuate ahead of the flames.

At least 50 homes, many of them mountain cabins, were also evacuated after they were threatened by the blaze, but U.S. Forest Service spokesman Manuel Madrigal said those orders would likely be lifted by evening.

"The winds are still not in our favor but it's going okay. I was just out on the fire lines and there wasn't any major burning activity," Madrigal said.

Madrigal said the fire had been driven by the strong winds and was burning dry chaparral, grass, brush and oak trees some six miles inland from Santa Barbara.

More than 560 firefighters were battling the blaze, which sent thick smoke over Santa Barbara, a city of more than 200,000 people about 80 miles northwest of Los Angeles.

Madrigal said campgrounds would remain closed and that the cause of the fire was under investigation.

(Reporting by Dan Whitcomb; Editing by Cynthia Johnston and Bob Burgdorfer)