Two fires merged together earlier to form the Mendocino Complex Fire, which is burning to the north of San Francisco.
The fire has destroyed 283,800 acres of land, almost the size of the whole city of Los Angeles and more than ten times the size of Paris.
President Donald Trump has declared a “major disaster” in the state, but has accused California’s environmental laws of “making things so much worse” on social media.
Elsewhere in the state, the Carr fire, which has claimed seven lives, continues to burn.
The catastrophic Carr fire has laid whole towns to waste, as 1,077 homes have been confirmed lost by California’s Department of Forestry and Fire Protection (Cal Fire).
The Carr fire is now 47 percent contained.
Despite the Mendocino Complex fire being greater in size, it has done comparatively less damage than the Carr fire.
75 homes have been destroyed, and no fatalities have been reported.
But today, as the Mendocino Complex twin fires merged, CalFire pushed their estimated date for the fire to be tackled for another month.
Ferguson fire, further south, has wreaked havoc, with three dead and the iconic Yosemite National Park having to close.
Across the state, more than 14,000 firefighters and hundreds of US army personnel are working to battle the fires.
National Weather Service meteorologists have warned conditions are not going to immediately improve, with temperatures as high as 43C (110F) being forecast for some areas.
Scott McLean, a CalFire deputy chief described the wildfires as “extremely fast, extremely aggressive, extremely dangerous.
“Look how big it got, just in a matter of days… Look how fast this Mendocino Complex went up in ranking. That doesn’t happen. That just doesn’t happen.”
It is thought that years of drought have resulted in dry vegetation across the state, allowing fires to spend rapidly.
The intense heatwaves sweeping the drought-stricken state have magnified the issue.
Scientists have said climate change is the underlying cause of all the factors which have added up to allow the fires to get out of control.
President Trump tweeted on Monday that “the fires are being magnified & made so much worse by the bad environmental laws which aren’t allowing massive amounts of readily available water to be properly utilised.”
But experts have disputed the President’s claim.
LeRoy Westerling, a climate scientist and associate professor at the University of California, said: “The problem here is he’s not acknowledging the role climate change is playing in California’s fire problem, and the scale of the problem is far beyond anything he’s talking about doing.”