The raging Mendocino Complex fire comprising twin blazes in the state's north has now ravaged almost 120,000 hectares - approximately the size of sprawling Los Angeles - in less than two weeks, becoming California's largest wildfire since record-keeping began a century ago.
Some 14,000 firefighters, including reinforcements from as far away as Australia and New Zealand, are combating the firestorm which remains just 34 percent contained.
The River Fire of the Mendocino Complex is 78 percent contained, having burned 48,920 acres. But its partner blaze the Ranch Fire has grown to 243,772 acres and is just 20 percent contained.
"Still a lot of work to do," said Charlie Blankenheim, a chief of fire fighting operations. "But we have got a plan for all of it, we think that in a day or two we are going to have some success and start to wrap this up."
Limited access, heavy fuel loads, low fuel moisture and high temperatures were all impeding firefighters' efforts to rein in the conflagration, the state's CalFire authority said.
Overall, the Mendocino Complex fire has destroyed at least 143 structures, 75 of them residences. More than 11,000 other structures are threatened, according to CalFire.
Newspaper headline: Calif. scorched by spreading wildfires the size of LA