As of Tuesday, more than 840 fires were burning throughout the state following lightning storms that swept through the state from the Oregon border south to Fresno, fire officials said. Particularly dry weather conditions made the situation worse.
Three crews of San Ramon Valley Fire Protection District firefighters were sent first to Watsonville and then to Napa/Solano counties to fight a blaze dubbed the "wild" fire.
Residents with respiratory-related health issues are encouraged to limit exposure and exertion while outside, said district spokeswoman Kimberly French.
"It's a good reminder for people to be very cautious and understand that we are under a red flag warning," she said.