The blaze destroyed 50 structures as it spread, and forced the evacuation of an estimated 1,000 people, officials said.
The cause of the fire, which began Friday, remains under investigation and evacuation orders for Weed, Lake Shastina and Edgewood, are in place.
The fire has prompted the evacuation of more than 300 people. Its cause is not yet known, according to Cal Fire.
Cal Fire Battalion Chief Jon Heggie told CNN Sunday afternoon fire conditions in California are “extremely dangerous,” given the state’s extended drought.
“What that left us with was a huge amount of dead fuel throughout California. So, all these fires now have just receptive fuel beds to burn and now when anything gets started it has that potential for exponential growth in a short period of time,” Heggie said. “There’s such a large amount of dead fuel, you know, basically from San Diego all the way to the Oregon border,” he said.
He warned the public to be careful engaging in any activities which could potentially start a fire.
“Dozers, hand crews and engines made great progress today further building containment line around the fire perimeter and will continue overnight. Over the next three days, the Route Fire will continue to be patrolled and monitored,” the fire department said.
It said the fire was expected to be fully contained by Wednesday.
CNN’s Amanda Musa and Susannah Cullinane contributed to this report.