SANTA ROSA, Calif. — Northern California officials ordered a new round of mandatory evacuations overnight Saturday for parts of the Sonoma Valley and eastern Santa Rosa as gusting winds returned, reviving dangerous fire conditions in a region that has been devastated by ongoing blazes since last week.

The National Weather Service warned Friday night that strong winds were expected throughout Northern California, with gusts of 35 to 45 mph, putting much of the region under a red flag warning.

“If any new fires start, they could spread extremely rapidly,” the NWS said. Dangerous winds and extremely dry “fuels” on the ground “also could cause problems with the current wildfires and the firefighters trying to suppress them,” the NWS noted.

Late Friday, the Sonoma County Sheriff’s Office recommended that residents in eastern Sonoma Valley be prepared to leave because of a blaze in the area, dubbed the Nuns Fire, that was only 10 percent contained. Shortly after 2 a.m. local time Saturday, the order was upgraded to a mandatory evacuation — with repeated notices underscoring the heightened urgency.

“If you live in the areas below, LEAVE NOW!” Sonoma County officials wrote Saturday. The evacuation order affected thousands of residents, as the Nuns Fire remained a “big, unwieldy beast,” a fire spokesman told KQED News.

In neighboring Napa County, to the east, officials said Saturday morning that they did not expect any new evacuations but cautioned residents to remain vigilant because of “significant wind activity.”

“Sonoma County has had a very tough morning with the winds that have surfaced over there. We’re not out of the woods and have work to do,” Napa County Fire Chief Barry Biermann said at a news conference Saturday morning. “But on our side of it, off of the Highway 29 area, we have pockets that are burning down into dry creek.”

Even as several fires still burn across hundreds of acres in the California wine country, the horrific scale of death and destruction is coming into focus.

At least 38 people have been confirmed dead in four counties, many of them elderly, some burned to ashes. One victim was 14 years old. (The Mendocino County Sheriff’s Office revised its death toll late Friday, from nine fatalities to eight.)

Taken together, the disastrous blazes — more than 20 in all since Sunday, including at least six in Sonoma County — have killed more people than any other California wildfire on record. The death toll is certain to rise as authorities — some accompanied by cadaver dogs — continue to explore the wreckage.

Hundreds are still missing. Statewide, an estimated 5,700 structures have been destroyed, including whole neighborhoods reduced to smoldering rubble. About 90,000 people have been displaced by the fires, officials said Friday.

“It’s devastating. I’ve only driven maybe 5 percent of the fire area . . . I don’t even think I understand what the damage toll is going to be, and I have a better handle on it than most,” Sonoma County Sheriff Rob Giordano told the Los Angeles Times. “Santa Rosa will be a different planet. There is so much to rebuild. It will absolutely change the community.”

Sonoma County, north of San Francisco, suffered the most damage, with 20 people confirmed dead and 223 still reported missing. The fires have destroyed nearly 3,000 homes and caused $1.2 billion in damage in Santa Rosa, the county seat and gateway to the wine tourism industry.

In Napa County, there were six confirmed fatalities as of Saturday afternoon; 74 people remain unaccounted for, out of the more than 200 reported missing over the past week.

Firefighters have made some significant gains. As of Saturday morning, some of the deadliest fires in Sonoma and Napa counties were nearly 50 percent contained, according to the California Department of Forestry and Fire Protection.

Biermann, the Napa County fire chief, said firefighting efforts Saturday would be focused on maintaining perimeter lines to keep existing blazes contained, even as they continued to burn.

As blazes are extinguished, counties have been preparing to let people return to evacuated areas.

“My commitment and top priority remains to bring back normalcy to this community,” Cal Fire Deputy Chief…