LOWER LAKE, Calif. -- Firefighters were working aggressively to regain control after a raging California fire jumped a highway that had served as a containment line for the massive blaze -- one of 20 wildfires burning in California.

Cooler weather had helped crews build a buffer Monday between the wildfire and some of the thousands of homes it threatened as it tore through drought-withered areas.

But Monday afternoon erratic wind blew hot embers across Highway 20, north of the city of Clearlake.

"There were too many (spot fires) for us to pick up," Battalion Chief Carl Schwettmann of the California Department of Forestry and Fire Protection told the San Francisco Chronicle, after the stand on Highway 20. "With these drought-stricken fuels, it's just moving at an extremely high rate of speed."

At least two dozen homes were destroyed over the past few days, and more than 13,000 people were urged to flee.

The fire -- the largest blaze in drought-stricken California -- roughly tripled in size over the weekend to almost 250 square kilometres, generating its own winds that fanned the flames and reduced thousands of acres of manzanita shrubs and other brush to barren land in hours.

Numerous other wildfires in California, Washington state and Oregon took off as the effects of drought and summer heat turned the West Coast combustible. California blazes killed a firefighter last week and injured four others.