LOS ANGELES - CALIFORNIA firefighters held the line overnight on two wildfires burning along the California coast that threatened more than 4,000 homes and other structures, fire officials said on Friday morning.

The Basin Complex and Gap fires, burning about 273km apart, were both unusually active overnight but firefighters managed to stop the flames, in some cases at the doorsteps of homes.

The Gap fire, burning north of Goleta, is considered the top priority among more than 1,000 blazes burning across the state because of its proximity to homes.

Although the blaze more than doubled in size to 2,185 hectares, firefighters turned it away from Goleta, a town of 30,000 people about 160km north-west of Los Angeles, and from power lines that supply the central California coast, said Santa Barbara County spokesman William Boyer.

'Our firefighters made some pretty heroic stands last night,' he said.

Mandatory evacuations and evacuation warnings, in which residents must be prepared to leave, remain in effect for 1,900 homes, Mr Boyer said.

A fleet of 20 firefighting aircraft began dropping water and retardant on the flames on Friday, and weather conditions were 'a little overcast and a little muggy', Mr Boyer said.

'If we get more of that, that's a good thing,' he said.

County health officials issued face masks to residents who planned vigorous outdoor activities to protect them from heavy smoke, Mr Boyer said.

While Goleta residents will miss their annual Independence Day fireworks display this year, the neighbouring city of Santa Barbara plans to go forward with its display, he said.

County officials had no containment figure for the Gap fire on Friday morning.

Farther up the coast, firefighters made no progress extending containment lines but turned the 26,460-hectare Basin Complex Fire away from threatened homes, fire information officer Karen McKinley said.

The Basin Complex Fire was 5 per cent contained on Friday morning - unchanged from the previous day, she said.

Flames are most active along the coast and the fire's southern edge, and firefighters worried about windy and dry conditions expected on Friday, Ms McKinley said.

The fire is burning in the foothills above the scenic coastal community of Big Sur, where 1,800 homes and businesses had been evacuated and 40 km of coastal highway shut down. Big Sur is about 225km south of San Francisco.

Those evacuations and closures remained in effect on Friday, Ms McKinley said. -- REUTERS