The swarming Dixie fire in Butte County, north of Sacramento, gained ground on Saturday and was only 21% contained as of Sunday, according to the California Department of Forestry and Fire Protection.
The Dixie fire joined with another one nearby on Saturday night, and firefighters have struggled to contain the blazes that have triggered evacuations in several communities.
Large fires like the Dixie fire and Oregon's Bootleg fire, a massive blaze that has blackened more than 408,000 acres and was 46% contained as of Sunday, can at times generate their own weather, like lightning storms.
With the Dixie fire encroaching, the Plumas County Sheriff's Office issued mandatory evacuation orders for the eastern shore of Lake Almanor where "personnel are conducting door to door notifications."
An evacuation shelter was established in the city of Susanville, and five other areas were placed under evacuation warnings.