A wind-stoked wildfire northeast of Sacramento burned dozens of homes Tuesday and has forced thousands of fire-weary residents to flee, state officials said. About 40 homes in the rural Butte County community of Concow were destroyed after erratic winds blew embers across fire containment lines, said Todd Simmons, a California Department of Forestry and Fire Protection spokesman. Firefighters went door to door early Tuesday to evacuate 800 to 1,000 residents from Concow and Yankee Hill, about 85 miles north of Sacramento. Residents of 3,200 homes were ordered to evacuate in nearby Paradise, where wildfire destroyed 74 homes last month. "Right now we're battling the weather and the erratic winds," Simmons said. "Whatever the winds are doing, that's pretty much what the fire's going to do." Winds as high as 30 mph fanned the blaze, one of about 30 lightning-sparked wildfires in the county that have charred 47,000 acres in recent weeks. Firefighters were also struggling against a sudden drop in humidity and a 10-degree spike in temperature as a heat wave forecast to linger until the weekend grips much of the state. The Butte County complex of fires was about 40 percent contained Tuesday night, officials said. Fire crews across the state have been straining to cover hundreds of active California wildfires, many of which were ignited by a lightning storm more than two weeks ago. A blaze threatening the small coastal community of Big Sur let up just enough to allow hundreds of people to check on their homes Tuesday. At least 23 homes and 25 other structures have been destroyed in Big Sur as flames marched over more than 125 square miles of land since June 21. Although that fire is far from controlled - the rugged terrain has kept containment at 18 percent into the fire's third week - authorities lifted the mandatory evacuation order issued for 25 miles of the 31-mile stretch along the Pacific Coast Highway that had been closed. Many of the 1,500 evacuated residents of Big Sur headed home Tuesday morning through smoke and ash, anxious to gauge the damage. Dena Angelique, 34, unloaded hastily packed bags of books, photos, art supplies and clothes from the back of her dusty Toyota 4Runner after a week away from her home. She was relieved to find the fire had stopped within 100 yards of her home, though it had charred the nearby mountainside. She wasn't sure how long she'd stay; smoke and ashes still floated among the blackened remains of oak and pine, burning her throat. "It was so insane watching the whole hillside burning," she said. "It's so nice to come back and know that we're safer here now." Officials, however, cautioned that the lifted evacuation orders did not mean conditions had drastically improved. A fire in the Los Padres National Forest near Santa Barbara grew slightly to 9,785 acres, or about 15 square miles, but the number of homes threatened dropped sharply Tuesday as crews secured fire lines near populated areas. The blaze continues to threaten about 250 homes, down from a peak of more than 3,000. The fire is 55 percent contained, said U.S. Forest Service spokeswoman Debbie Becker. "It's going according to plan," Becker said "They've really got a good hold on this fire but there's still a lot of potential to get worse. ... It's a fuel-driven fire and there's still a lot of fuel out there." Marine fog, relatively calm winds and moderate temperatures from Tuesday morning helped firefighting efforts on the lower flanks of the Santa Ynez Mountains, where helicopter water drops doused flames in the rugged canyons, Becker said. Temperatures on Wednesday and Thursday are expected to spike into the 90s, and fire officials worry that the flames will reach above 1,300 feet where the brush is very dry, Becker said. About a dozen homes along the ridgeline overlooking the Pacific Ocean remain under a mandatory evacuation order. In some parts of California's Central Valley, temperatures were forecast to climb close to 110 degrees Tuesday. The agency that monitors the state's power grid said peak energy demand could approach the record set in July 2006, and it asked customers to reduce their late-afternoon power consumption. The expected heat wave raised not only the fire danger, but also concerns about heat illness among firefighters worn down by the long fight against blazes that have consumed more than 985 square miles in California since late June. "We do have a lot of fatigue because of the low numbers of resources in the state," said Thom Walsh, a Forest Service resource unit leader. Crews took rest breaks in refrigerated trailers with bunk beds before returning to the field, but heat stroke was a worry, Walsh said.