The move will unlock additional support from Washington, including allowing the Federal Emergency Management Agency and Department of Homeland Security to coordinate relief efforts.
Nearly 200,000 people have been forced from their homes across the state as more than 5,700 firefighters fight to keep the situation under control.
And strong winds predicted this weekend threaten to make the problem worse by fanning the flames.
At least 500 homes and businesses have been destroyed so far.
The blazes stretch from San Diego in the south up to Santa Barbara County, north of Los Angeles.
Forecasts from the National Weather Service today warned of “extreme fire danger conditions” all weekend as dry winds gusting at up to 50mph blast in from across the arid California desert.
The California Department of Forestry and Fire Protection (CAL FIRE) said that wind and weather conditions would increase risks from the Los Padres National Forest, north of Santa Barbra, all the way down the coast to the Mexican border.
Three of the largest blazes in Ventura and Los Angeles counties are threatening around 86,000 homes, which if destroyed, could cost more than $27billion to rebuild, according to New Jersey-based risk analysis firm CoreLogic.
This is a breaking news story. More to follow.