Nearly 330 firefighters aided by cooler conditions overnight worried the fire could spread if winds kicked up and temperatures rose, said Barry Peckham, a Santa Barbara County Fire Department spokesman. Temperatues could reach 90 degrees, he said.
``There's quite a potential for extreme fire behavior,'' he said.
The blaze broke out before noon Saturday in a section of the Gaviota Pass, about 27 miles north of Santa Barbara, and burned across narrow canyons and steep hillsides covered with chaparral.
About 500 people in roughly 200 homes in the gated community of Hollister Ranch were evacuated. No injuries were immediately reported.
A nearly 3-mile-stretch of Highway 101 remained closed Sunday morning in both directions after plumes of smoke and fiery embers cut visibility and forced authorities to divert traffic, Peckham said.
The Arguello and Shell Oil refineries were threatened but undamaged. At least one structure, part of an abandoned school, was damaged by the flames.
Firefighters had no estimate on when the fire might be contained. The cause was under investigation.