(WineSpectator) - Dozens of wineries evacuated as the Valley fire destroys hundreds of homes and displaces thousands; Napa vineyards could be threatened, with Howell Mountain already evacuated

Northern Californians are again finding themselves at Mother Nature's mercy. Yet another wildfire erupted in dry, drought-stricken Lake County on the afternoon of Saturday, Sept. 12. It's the county’s fourth this year, by far the most destructive to date.

The blaze has quickly spread south and east, to the borders of Napa and Sonoma counties, scorching at least 67,000 acres and more than 580 homes as of Tuesday morning. State authorities report that roughly 15 percent of it has been contained, as cooler weather in the past 24 hours has helped fire teams' efforts.

The quick-moving “Valley Fire” started on Saturday afternoon and grew quickly, charring a 40-square-mile swath—nearly the size of San Francisco—in just six hours. More than 2,300 firefighters are working to control the blaze, establishing firebreaks around the affected area. Approximately 20,000 people have been evacuated; an elderly woman unable to escape her home died in the fire. Four firefighters suffered serious burns.

Dozens of wineries and vineyards are inaccessible due to the fire, and more than 5,000 buildings are without power, bringing harvest to a halt in the emerging wine region due north of Napa, where Howell Mountain and its prized Cabernet vineyards have already been evacuated.

Langtry winery, in Lake County's Guenoc Valley just east of Middletown, was forced to evacuate over the weekend; staff returned today to find the fire damage less than feared. "Langtry Winery is back up and running—powered by a generator," e-mailed Andrea Smalling, chief marketing officer for Foley Family Wines, Langtry's parent company. "It’s likely that we won’t be able to harvest the remaining grapes due to smoke damage, but our winemaker is doing lab work to confirm … the actual damage to vineyards may not be as bad as we initially thought—there are areas of green once you get past the most outer vines." One of the homes on the Langtry property was destroyed in the fire, but the historic Lillie Langtry home was saved.

Another severely impacted wine region is Red Hills, which lies in the southwestern corner of Lake County, where Napa-based grower Andy Beckstoffer has 1,500 acres planted. His vineyards are west and north of the current fire, but vineyard crews are unable to access the area because of closed roads. “Harvest is on hold,” Beckstoffer toldWine Spectator. For vineyards lucky enough to dodge the fire, there are still concerns that smoke taint may affect the grapes, and that picking crews may be unavailable or unable to get to the vineyards.

Dave Guffy, director of winemaking at The Hess Collection, said he's waiting and watching to determine when and how he can get the fruit from Hess' Lake County vineyards into the winery. “These grapes are the backbone of the Hess Select red programs," Guffy said. "All we can do is evaluate as we go, but we’re hopeful and optimistic and, like all, focused on the safety and security of our community.”

Guffy said they were set to begin picking grapes from a vineyard in Napa's Pope Valley as well, but have not been granted access to the roads necessary to get equipment and people in.

Severe drought conditions have created a volatile fire season in California. There have been more than 5,000 fires to date, burning more than 215,000 acres. But this isn't even the worst season of the past decade. 2008, which many vintners on California's North Coast recall for its smoke-tainted grapes, was the largest fire season in California history. That year, 1,375,781 acres burned throughout California.

Nearby communities are extending a helping hand, providing shelter and donations to those affected. The Napa County Fairgrounds in Calistoga has taken in hundreds, as well as their animals, including horses, cows and dogs.

The fire continues to push in all directions. The Geysers of Sonoma County, the world's largest geothermal field and home to 22 power plants, is also threatened by the Valley fire—three buildings in the geothermal fields have already burned. The fires are also pushing southeast toward Napa Valley’s Angwin, where more than two dozen wineries are located, including Schrader and Cade. Much of the population there has been evacuated, and even residents in Calistoga are on alert to brace for evacuation.