Northern California’s wine country is on fire again as strong winds fanned flames in the already scorched region, prompting evacuation orders involving more than 50,000 people.

Residents of Oakmont Gardens assisted living home in Santa Rosa boarded brightly lit city buses overnight, some wearing dressing gowns and using walkers. They wore masks to protect against coronavirus as orange flames marked the dark sky.

Flames also engulfed the Chateau Boswell Winery north of St Helena. Adventist Health St Helena hospital suspended care and transferred all patients elsewhere, according to a statement on its website.

“We just don’t have words,” state senator Mike McGuire told KTVU-2 in Oakland. “It’s an incredibly trying and emotional time right now.”

The fires that began on Sunday in the famed Napa-Sonoma wine country north of San Francisco came on the third anniversary of deadly wildfires that erupted in 2017, including one that killed 22 people.

The latest began with the Glass Fire on Sunday morning and two subsequent blazes merged with it, burning 17 square miles by early Monday, according to the California Department of Forestry and Fire Protection (Cal Fire).

Officials did not have an estimate of people under evacuation but Paul Lowenthal, Cal Fire spokesman, said more than 13,000 homes were threatened in Santa Rosa alone. He estimated tens of thousands of people are under evacuation warnings or orders.

“In some parts of Santa Rosa, they’re mopping up hot spots,” he said. “In other parts, they’re still actively fighting fire.”

Numerous studies in recent years have linked bigger wildfires in America to global warming from the burning of coal, oil and gas, especially because climate change has made California much drier.

Evacuations were also ordered in Shasta County as the Zogg Fire spread over 23 square miles. Residences are widely scattered in the forested area, about 10 miles south west of the city of Redding in a region torched two years ago by the massive and deadly Carr Fire — infamously remembered for producing a huge tornado-like fire whirl.

The causes of the new fires are under investigation.

They erupted as a giant ridge of high pressure settled over the West, producing powerful gusts blowing from the interior towards the coast while slashing humidity levels and raising temperatures, making vegetation ready to burn.

Flames consume a house in Oakmont
Flames consume a house in Oakmont (Noah Berger/AP)

During the weekend, Pacific Gas & Electric turned off electricity to targeted areas where the winds raised the potential for arcing or other power equipment damage that could spark new fires.

The utility’s equipment has caused previous disasters, including the 2018 Camp Fire that devastated the Sierra Nevada foothills town of Paradise and killed 85 people.

So far this year, more than 8,100 California wildfires have scorched 5,780 square miles, destroyed more than 7,000 buildings and killed 26 people.

Most of the losses occurred after a frenzy of dry lightning strikes in mid-August ignited a massive outbreak of fires.

Fire worries are also developing across southern California although it was unclear how strong predicted Santa Ana winds would be.

Conditions were also hot, dry and windy in parts of Arizona, where the Sears Fire in Tonto National Forest, north of Phoenix, has grown to more than 14 square miles since it erupted on Friday afternoon.