Firefighters battling an explosive wildfire near Yosemite National Park significantly slowed the spread of the flames, but thousands of residents of mountain communities remained under evacuation as smoke drifted toward Lake Tahoe, parts of Nevada and the San Francisco Bay Area.
More than 2,500 firefighters supported by aircraft were battling the blaze, known as the Oak Fire, which broke out last Friday near the town of Midpines, California. Officials described “explosive fire behavior” on Saturday as flames tore through bone-dry vegetation covered by the worst drought in decades.
As of Tuesday morning, the fire had consumed more than 18,000 acres of land in the Sierra Nevada foothills, with 26 percent containment, the California Department of Forestry and Fire Protection, or CalFire, said. At least 55 homes and structures had been burned.
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“Persistent drought, very dry fuels and tree mortality continue to contribute to the fire’s spread,” CalFire said Tuesday morning, but moisture levels were slightly higher, aiding crews in their fight against fires
By Monday, helicopters had dropped 300,000 liters of water on the fire, the agency said.
Evacuations were ordered Monday for more than 6,000 people living in a several-mile swath of the sparsely populated fire zone, though a handful of residents defied orders and stayed behind, spokeswoman Adrienne Freeman said of the US Forest Service.
“We urge people to evacuate when told to,” he said.
The cause of the fire remained under investigation.
Smoke from the fire shrouded views of Yosemite National Park in a thick gray haze on Monday as the air quality index (AQI) topped 250, a level classified as very unhealthy. The smoke also produced poor visibility north of the fire during the day and across the fire at night, CalFire said.
Smoke drifted more than 200 miles (322 km) to reach parts of northern California and Nevada.
There are two major wildfires in California, which is experiencing a fairly typical increase in what will likely be an active fire year once California’s infamous Santa Ana and Diablo wind events begin in September, said Kim Zagaris, a consultant with Western . Association of Fire Chiefs, which maps wildfires across the country.
“We were lucky. We’re not as far along as we were this time last year,” he said. “But the fuels, the vegetation, is a lot drier than last year. It’s very dry out there.”
Zagaris compared wildfires in California this year to 2008, when few fires burned early, but a midsummer lightning strike hit the state “and before we knew it, there were 2,000 fires burning in the northern part of the state”.
Fires are an important part of California’s climate and are essential to the health of landscapes and ecosystems across the state, but conditions have changed, causing some fires to become catastrophic. The largest and deadliest wildfires in recent years have increased as a history of fire suppression allowed landscapes to grow densely vegetated.
The climate crisis has left the West much warmer and drier, baking moisture from overgrowth and setting the stage for larger, more erratic burns. Scientists have said the weather will continue to become more extreme and wildfires more frequent, destructive and unpredictable.
Numerous roads were closed, including a stretch of State Route 140 which is one of the main routes into Yosemite. Public utility Pacific Gas & Electric (PG&E) said on its website that more than 2,600 homes and businesses in the area had lost power as of Monday and there was no indication when it would be restored.
The Oak fire was sparked as firefighters advanced against an earlier Washburn fire that burned to the edge of a giant sequoia forest in the southernmost part of Yosemite National Park.
The latter fire, which covered an area of 19 km², was 87% contained on Monday after burning for two weeks and moving into the Sierra National Forest.