The Associated Press

OROVILLE, Calif. — Thousands of people were ordered to get out of Paradise on Wednesday as an out-of-control wildfire threatened the Northern California city that also was devastated by flames just weeks ago.

Authorities ordered residents of 3,200 Paradise homes to evacuate after the wind-stoked fire destroyed 40 homes and 10 structures Tuesday in the nearby rural community of Concow. Evacuation orders remained in effect for 1,000 residents of Concow and Yankee Hill, about 85 miles north of Sacramento.

Officials said more than 3,800 homes were threatened by the flames Wednesday. Another wildfire destroyed 74 homes in Paradise last month.

Two shelters were full Wednesday morning with 500 evacuees, said Melissa Smith, spokeswoman for the California Department of Forestry and Fire Protection, or Cal Fire.

The blaze had flared up early Tuesday after erratic winds blew embers across fire containment lines.

"Right now we're battling the weather and the erratic winds," said Todd Simmons, another Cal Fire spokesman. "Whatever the winds are doing, that's pretty much what the fire's going to do."

Firefighters were facing a sudden drop in humidity and a 10-degree spike in temperatures as a heat wave, forecast to linger until the weekend, grips much of the state.

About 30 lightning-sparked wildfires in Butte County, where Paradise and Concow are located, have charred 47,000 acres in recent weeks and were about 40 percent contained, officials said.

Among those evacuated Tuesday were 95 children at a camp for kids with cancer, 70 miles north of Sacramento.

"They've been remarkably good," Michael Amylon, the camp's medical director, said of the children. "We always talk about fire being a danger."

Fire crews across the state have been trying to cover hundreds of active California wildfires, many of which were ignited by a lightning storm more than two weeks ago. Some 1,450 fires had been contained late Tuesday, but more than 320 were still active, authorities said.

Two hundred National Guard troops were to complete their training in wildfire fighting Wednesday and join the more than 18,000 personnel battling blazes around the state.

At a fire east of Bakersfield on Tuesday, wind gusts caused flames to jump fire lines and destroy or damage five residences and four more outbuildings in the Sequoia National Forest.

A blaze threatening the popular coastal community of Big Sur let up just enough to allow hundreds of people to check on their homes Tuesday. Authorities announced that more residents would be allowed to return Wednesday morning.

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 23 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. Officials, however, cautioned that the lifted evacuation orders did not mean conditions had drastically improved.

A wildfire 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."

In addition to heightening the fire danger, the heat wave raises 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, Walsh said.

Highs are likely to be in the triple digits across much of the northern half of the state until at least Friday, National Weather Service forecaster Christine Riley said.

Temperature records for the date were broken in five cities Tuesday, including Sacramento, where the temperature reached 108, breaking the previous high of 104 degrees set in 1997. Modesto hit 107.