Crews were digging in and burning out fire lines amid fears that another round of high winds on Saturday could bring renewed fury to a northern California wildfire.
“We have a firefight ahead of us and the wind today is going to make it very challenging,” said Keith Wade, a spokesman with Cal Fire.
The Caldor fire in the northern Sierra Nevada has destroyed dozens of homes, and authorities on Friday closed down a 46-mile (74 km) stretch of Interstate 50, the main route between the state capital, Sacramento, and Lake Tahoe on the Nevada state line.
The highway was closed after debris from the blaze fell on to the roadway and because of red flag warnings for 20- to 30mph winds that could gust to 40mph throughout Saturday. The road is a key checkpoint as crews struggle against the fire, which erupted earlier this week and grew to 10 times its size in a few days, fueled by winds.
“We’re going to invest everything we can into holding the fire south” of the road, said Eric Schwab, an operations section chief with Cal Fire.
Firefighters made progress on the fire’s western side and burned vegetation to starve it of fuel and prevent the flames from heading into the evacuated community of Pollock Pines. On the north-east side, crews were protecting cabins in the dense forest area, fire officials said.
The Caldor fire had devoured about 82,000 acres (33,000 hectares) as of Saturday and more than 1,500 firefighters were battling it amid heavy timber and rugged terrain.
The blaze was one of about a dozen large California wildfires that have scorched northern California, incinerating at least 700 homes alone in and around the Sierra Nevada communities of Greenville and Grizzly Flats.
To the north-west of the Caldor fire, the massive Dixie fire kept expanding and new evacuations were ordered, including the tiny hamlet of Taylorsville. In five weeks, the fire about 175 miles north-east of San Francisco has become the second-largest in state history and blackened an area twice the size of Los Angeles.
The fires have burned nearly 1.5m acres (607,000 hectares) and have sent smoke as far as the east coast. They were burning in grass, brush and forest that is exceptionally dry from two years of drought likely exacerbated by climate change.
Thousands of homes remained under threat in communities tucked away in scenic forests and tens of thousands of people remain under evacuation orders. Nine national forests in the region have been closed because of the fire threat.
Forecasts call for a storm system that will bring winds but little rain into early next week. With it will come increased risks of fires. Dozens have erupted in recent days but were quickly stamped out.
An exception was the Cache fire, a small but fast-moving grass blaze that ravaged at least 56 homes and virtually annihilated a mobile home park.
California is one of a dozen mostly western states where 99 large, active fires were burning as of Friday, according to the National Interagency Fire Center.
Fires have intensified across the west, creating a nearly year-round season. Fire patterns used to migrate in seasons from the south-west to the Rockies, to the Pacific north-west and then California, allowing crews to move from one place to the next, said Anthony Scardina, deputy regional forester for the US Forest Service.
“But the problem is all of those seasons are starting to overlap,” Scardina said.
On Saturday, there was even bad news in northern Minnesota, as the US Forest Service closed the 1m-acre Boundary Waters canoe area wilderness due to the largest active wildfire in the state.
It was not known if campers already in the expansive wilderness area would be evacuated. The closure included all land, water, trails, portages, campsites, canoe routes and wilderness entry points and was put in place until 27 August.
The Boundary Waters in the Superior national forest is one of the most visited federally designated wilderness areas. The Greenwood fire in the forest remained uncontrolled on Saturday and had spread to about 9,000 acres (3,600 hectares). Nearly 300 firefighters were battling the blaze.