The raging blazes have killed several people, injured hundreds and forced thousands to evacuate.
The still-raging Dixie Fire in northern California is now the second-largest in the state’s history, officials said on Sunday, days after the blaze destroyed an historic town and forced the evacuation of thousands of people from the area.
California fire authorities said in a Sunday morning update that the wildfire now spanned 187,562 hectares (463,477 acres) and remained only 21 percent contained, but that favourable conditions would allow crews to battle the flames.
“Fire activity is expected to decrease through the morning hours. Smoke shading from fires in the region will reduce fire intensity, increasing the potential for crews to make headway on building containment lines,” officials said in a statement (PDF).
At least 404 structures have been destroyed by the fire so far, the statement also said, while more than 13,800 others are under threat.
Only the August Complex Fire, which consumed more than 404,700 hectares (1 million acres) in California in August of last year, was bigger.
Heatwaves and historic drought tied to climate change have made wildfires harder to fight in the western United States.
Scientists have said climate change has made the region much warmer and drier in the past 30 years and will continue to make the weather more extreme and wildfires more frequent and destructive.
In June, experts told Al Jazeera that US President Joe Biden should take up an ambitious, long-term strategy to mitigate wildfires fuelled by climate change, including providing more funding to help authorities thin out dense forests that pose a fire hazard.
Back in California, the Dixie Fire this week destroyed all of downtown Greenville, an old mining town about 257km (160 miles) north of Sacramento.
“We knew we didn’t get enough rainfall and fires could happen, but we didn’t expect a monster like this,” local resident Kesia Studebaker told The Associated Press news agency.
On Saturday, the Plumas County sheriff’s office said it had received descriptions of five people considered missing in Greenville and was searching for them. Five other missing people were confirmed found that day.
The cause of the blaze, which has now spread to an area larger than the city of Houston, Texas, remains under investigation.
Pacific Gas & Electric has said it may have started when a tree fell on one of the utility’s power lines.