Meteorologists said fresh northerly winds were likely to drive the flames from the fire – named Thomas – towards the Pacific coast.
The blaze, the state’s third largest on record, has now burnt almost 1,000 sq km (405 sq miles) since 4 December.
Two people are reported to have died as a result of the fire.
Fire apparatus engineer Cory Iverson was killed tackling the blaze last week, along with a woman, Virginia Rae Pesola, who was in a car crash as she evacuated.
The resurgence of strong “sundowner” winds combined with low humidity forecast for Sunday could fuel the flames and has prompted new mandatory evacuation orders for several Santa Barbara communities, including hillside homes in Montecito and Summerland.
The fire has crossed the San Ysidro canyon, dashing firefighters’ hope that it could be contained.
More than 8,000 firefighters are now tackling the blaze, which has destroyed about 1,000 structures including some 750 homes. The cost of the operation is now $104m (£78m), said Reuters news agency.
Using helicopters and planes to drop fire retardant on the flames, firefighters have managed to contain 40% of the blaze. (Courtesy BBC)