Winds have whipped new life into northern California wildfires that have killed a woman, injured firefighters, and reduced hundreds of homes to smouldering ruins.
"It breaks my heart to look out and see what you folks are going through," Lake County Sheriff Brian Martin told hundreds of evacuees given refuge on fair grounds in the wine country town of Calistoga.
"It is a terrible tragedy."
State disaster officials said two fast-moving infernos - dubbed the Valley and Butte fires - had destroyed more than 50,000 hectares, forcing thousands to flee.
Officials said the victim, who was not identified, died in the Cobb area of Lake County that has been especially hard hit.
The woman had a disability and emergency workers slammed with calls for help did not get to her home before it was engulfed in flames.
This marks the first civilian fatality in the wildfires that have devastated the western United States in recent months.
While the Valley fire is located about 160 kilometres west of the state capital Sacramento, the Butte fire is about the same distance to the east.
Cool, moist weather that moved into the area on Monday (local time), bringing with it chances for rain, brought welcome relief for crews who had been working on rough terrain in searing, dry heat days earlier.
However, the weather change also brought with it winds that powered swift moving walls of flames.
"The fire is definitely more active today than it was yesterday," Incident Commander Barry Biermann told AFP. "The fire is still spreading in different directions."
The hamlet of Middletown in Lake County was reduced to rubble by the flames that left an apocalyptic scene.
An AFP reporter who visited the town saw smouldering homes, melted vehicles and downed power lines.
"There is metal dripping off the cars because of the heat," he said.
About a mile outside of the town lay a dead horse by the side of the road.
Many residents in the region said the air was so thick with smoke, it was difficult to breathe.
The prolonged dry spell has been exacerbated by record high temperatures, which many environmentalists blame on global warming.