Winds are expected to pick up Thursday, prompting an expansion of evacuation advisories in some areas.
A fire official said this is the deadliest week of wildfires in California history.
Cal Fire has expanded evacuation advisories for the wildfires in Napa, Sonoma and Solano counties. Authorities said 17 of the 31 reported deaths come from Sonoma County.
The names of 10 victims who died in Sonoma County were released late Thursday by the Sonoma County Sheriff's Department. One of them is a 75-year-old woman from Apple Valley who was vacationing in Santa Rosa with her family.
-Carmen Caldentey Berriz, 75 years old from Apple Valley
-Carol Collins-Swasey, 76 years old from Santa Rosa
-Lynne Anderson Powell, 72 years old from Santa Rosa
-Arthur Tasman Grant, 95 years old from Santa Rosa
-Suiko Grant, 75 years old from Santa Rosa
-Donna Mae Halbur, 80 years old from Larkfield
-Leroy Peter Halbur, 80 years old from Larkfield
-Valerie Lynn Evans, 75 years old from Santa Rosa
-Michael John Dornbach, 57 years old from Calistoga
-Veronica Elizabeth McCombs, 67 years old from Santa Rosa
In Napa County, advisories were issued for people living east of Silverado Trail, Soscol Avenue, Highway 221, Highway 29 and north of Jameson Canyon Road.
In Sonoma County, advisories were issued for Palomino Lakes as well as parts of Windsor and Healdsburg. In Solano County, advisories were issued north of Jameson Canyon Road and I-80 and west of Suisun Valley Road.
An evacuation advisory means residents should prepare to leave if the situation worsens.
The wildfires are already well on their way to becoming the deadliest and most destructive in California history. If the blazes gain momentum Thursday, it could erase even the modest gains firefighters have made.
Steady winds with gusts up to 45 mph with nearly non-existent humidity are expected to descend on the areas north of San Francisco, where at least 24 people have died, hundreds more are missing and at least 3,500 homes and businesses have been destroyed.
"It's going to continue to get worse before it gets better," state fire Chief Ken Pimlott said Wednesday.
Entire cities had evacuated in anticipation of the next wave, their streets empty, the only motion coming from ashes falling like snowflakes.
They included Calistoga, the historic resort town of wine tastings and hot springs, whose 5,300 people are all under evacuation orders. Tens of thousands more were also driven from their homes by the flames. A few left behind cookies for firefighters and signs that read, "Please save our home!"
The 22 fires spanned more than 265 square miles as they entered their fourth day, many of them completely out of control. Modern, strategic attacks that have kept destruction and death tolls low in recent years just haven't worked against their ferocity.
"We are literally looking at explosive vegetation," Pimlott said. "Make no mistake," he later added, "this is a serious, critical, catastrophic event."
The community of Boyes Hot Springs in Sonoma County also was told to clear out Wednesday, and the streets were quickly lined with cars packed with people fleeing.
"That's very bad," resident Nick Hinman said when a deputy sheriff warned him that the driving winds could shift the wildfires toward the town of Sonoma proper, where 11,000 people live. "It'll go up like a candle."
The ash rained down on the Sonoma Valley, covering windshields, as winds began picking up. Countless emergency vehicles sped toward the flames, sirens blaring, as evacuees sped away. Residents manhandled canvas bags into cars jammed with possessions or filled their gas tanks.
PHOTOS: Deadly fires burn in Napa, Calistoga areas
Authorities said 8,000 firefighters and other personnel were battling the blazes and more resources were pouring in from Arizona, Nevada, Washington and Oregon.
To the south in Orange County, cooler weather and moist ocean air helped firefighters gain ground against a wildfire, dubbed Canyon Fire 2, that has scorched nearly 14 square miles
Orange County fire officials said on Wednesday that Canyon Fire 2 was 60 percent contained and full containment was expected by Saturday, although another round of gusty winds and low humidity levels could arrive late Thursday.
PHOTOS: Canyon 2 Fire destroys homes, prompts evacuations in Orange County
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KGO-TV and the Associated Press contributed to this report