CALISTOGA, Calif. — Firefighters face another devastating round of the low humidity, dry foliage and strong weekend wind gusts up to 60 mph Friday as they battle more than 20 blazes in the deadliest week of wildfires in state history. 

The death toll from Northern California's relentless wildfires increased to 31 with a report from Sonoma County Sheriff Robert Giordano Thursday night of two more fatalities.

“We had series of statewide fires in 2003, 2007, 2008 that didn’t have anything close to this death count,” said Daniel Berlant, a deputy director with the California Department of Forestry and Fire Protection.

Over 8,000 firefighters are battling the 21 wildfires that have burned 191,437 acres. At least 3,500 homes and businesses have been destroyed and an estimated 25,000 people forced to flee.

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Among the structures decimated was the Santa Rosa home of "Peanuts" creator Charles Schulz. His 78-year-old widow Jean Schultz escaped the house, which burned to the ground, her stepson said Thursday.

The Schulzes built the California split-level home in the 1970s and the cartoonist lived there until his death in 2000.

Schulz usually worked at an outside studio and most of his original artwork and memorabilia are at the Charles M. Schulz Museum and Research Center in Santa Rosa, which escaped the flames.

The biggest blaze, known as the Tubbs Fire, has destroyed 34,770 acres and is only 10%  contained in Sonoma County and part of Napa County, the state's wine country. It is one of five fires burning in the two counties.

Overnight, according to CalFire, a new large wildfire broke out in Fresno County southeast of the Bay Area and fire officials warned that conditions were ripe for new outbreaks.

Red Flag Warnings, forecasting dangerous fire conditions, are already in effect for much of Northern California as well as a stretch from near Santa Barbara to north of Los Angeles in Southern California.

"Red Flag Warnings for gusty winds and low humidity remain in effect across the fire area and much of Northern California," CalFire said in a statement. "These winds will continue to challenge firefighters in their efforts towards containment and will increase the risk for new fires." 

Forecasters warned that wind gusts could hit 60 mph in the higher elevations of the fire-ravaged areas, raising the danger that sparks will be blown into the parched areas and set off more fires among the dry brush and timber.

"A disturbance sweeping across northern California will cause an increase  in northerly winds and gusts this evening through Sunday," the Sacramento office of the National Weather Service said in a statement. "The combination  of wind and low relative humidities will create critical fire weather  conditions for much of the forecast area.  Temperatures will continue to  increase with decreasing humidity through Monday before temperatures begin  to cool heading into the middle of next week."

Santa Rosa and Sonoma County officials said Friday the damage continues to grow from fires ravaging the area, but that rebuilding has also begun. Authorities are also threatening prosecutions after warnings about reports of looting or people imitating emergency officials during the crisis.

Santa Rosa has lost 5% of its housing and has damage of at least $1.2 billion, according to Mayor Chris Coursey.

“It’s a huge hill that we’ve got to  climb,” Coursey said.

Shirlee Zane, chairman of the Sonoma County board of supervisors, said 22 shelters are open and providing services including mental-health counseling. But she said rebuilding has begun, with 1,400 building inspections completed already.

“We know these are stressful and taxing times,” Zane said. “People have gone through a tremendous amount of loss and grief is beginning to set in.”

Brett Gouvea, unified incident commander for firefighters, said there were concerns about 40 mph winds forecast for Friday afternoon. But officials are also working to return evacuees to their homes as quickly as possible.

“We don’t want to keep anyone out of their homes one minute longer than we have to,” he said. “Rest assured we are using every tool in the toolbox to mitigate this situation.”

Santa Rosa Fire Chief Tony Gossner said two hospitals are closed – Sutter Santa Rosa Hospital and Kaiser Permanente Santa Rose Medical  Center – but that Kaiser was expected to open within 12 hours.

“We’re really close to reopening Kaiser hospital, but we have a few more hurdles to tackle on that,” Gossner said.

Sonoma County Sheriff Rob Giordano said 1,308 were reported missing so far, but 1,052 have been located safe. Among the 256 outstanding, Giordano said 45 officials are searching specific properties. He said 18 people have died in the county so far.

Mike Palacio, a commander with the California Highway Patrol, asked for cooperation in keeping out of the way of emergency vehicles. When areas are closed for evacuation, he said officers couldn’t bend the rules to let one person in because others would follow.

“We cannot let you in there, with very little exception,” Palacio said. “We realize everyone has losses and we sympathize with that.”

Sonoma County District Attorney Jill Ravitch said authorities have begun receiving reports of looting. She warned that she will prosecute. Santa Rosa has a curfew and violators will be jailed, she said.

“The message that should be loud and clear is that no looting is going to be tolerated in this county,” she said.

Ravitch also said price gouging won’t be tolerated. If prices rise more than 10%, she urged residents to report it.

“That will not be tolerated,” Ravitch said.

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Contributing: Bart Jansen; Associated Press