0739 GMT August 15, 2018
As of late Sunday, the so-called Clayton Fire was burning through 3,000 acres (1,200 hectares), with 1,044 personnel fighting the blaze, according to state firefighting agency Cal Fire, AFP reported.
At least 10 homes and businesses have been destroyed since the fire broke out around 5:00 pm on Saturday (0000 GMT Sunday).
Only five percent of the blaze, located more than160 kilometers (100 miles) north of San Francisco, has been contained.
"The recent sustained, high temperatures around the state and historic statewide drought have made an ideal environment for dangerous fire conditions throughout California," the California Office of Emergency Services said in a statement.
"The terrain is grassy oak woodland with heavy brush and has created difficult firefighting conditions," it added.
The agency obtained a grant from the Federal Emergency Management Agency to help local authorities gather the necessary resources to fight the fire.
"The fire is burning aggressively towards the north, crossing Morgan Valley Road and Cache Creek, and is impacting the communities of Lower Lake and Clearlake," Cal Fire said.
"The fire behavior remains intense. Structures are threatened and currently mandatory evacuations are in place," it added, noting that it was challenging to access the terrain.
The community is still reeling from last year's devastating Valley Fire that killed four people, destroyed more than 1,300 homes and burned through more than 76,000 acres.
"We are going to recover and Lake County is going to come back strong," state senator Mike McGuire told a community meeting and press conference.
"Emotions are still incredibly raw from the Valley Fire," he added, noting that mental health professionals were being sent to the area.
The fire is only one of several burning throughout the most populous US state.
More than 4,100 personnel are fighting that blaze north of Big Sur, one of the region's most popular tourist draws with its sharp cliffs rising above the Pacific Ocean.
Authorities blame that inferno, which has destroyed 57 homes and 11 outbuildings, on an illegal campfire. It is now 60 percent contained.