Fire officials ordered more evacuations around the Tahoe Basin as the two-week-old Caldor fire encroached on the threatened mountain towns surrounding Lake Tahoe.
By nightfall, all residents on the California side of the Lake Tahoe Basin were warned to evacuate, after fire officials stressed for days that protecting the area was their top firefighting priority.
More than a dozen large fires are being fought by more than 15,200 firefighters across California. Flames have destroyed about 2,000 structures and forced thousands to evacuate while blanketing large swaths of the west in unhealthy smoke.
The California fires are among nearly 90 large blazes in the US. Many are in the west, burning trees and brush desiccated by drought. Climate change has made the region warmer and drier in the past 30 years and will continue to make the weather more extreme and wildfires more destructive, according to scientists.
“Today’s been a rough day and there’s no bones about it,” Jeff Marsoleis, forest supervisor for El Dorado national forest, said on Sunday evening.
A few days ago, he said, he thought crews could halt the Caldor fire’s eastern progress, but “today it let loose”.
Flames churned through mountains just a few miles south-west of the Tahoe Basin, where thick smoke sent tourists packing.
“To put it in perspective, we’ve been seeing about a half-mile of movement on the fire’s perimeter each day for the last couple of weeks and today this has already moved at 2.5 miles on us, with no sign that it’s starting to slow down,” said Cal Fire division chief Erich Schwab.
Some areas of the northern California terrain are so rugged that crews had to carry fire hoses by hand from Highway 50 as they sought to douse spot fires caused by erratic winds.
Triple-digit temperatures were possible and the extreme heat was expected to last several days. A red flag warning for critical fire conditions was issued for Monday and Tuesday across the Northern Sierra.
The blaze that broke out on 14 August was 19% contained after burning nearly 245 square miles (635 sq km), an area larger than Chicago. More than 600 structures had been destroyed and at least 18,000 more were under threat.
The Caldor fire has proved so difficult to fight that fire managers pushed back the projected date for full containment from early this week to 8 September. Even that estimate was tenuous.
In southern California, a section of Interstate 15 was closed on Sunday afternoon after winds pushed a new blaze, the Railroad fire, across lanes in the Cajon Pass north-east of Los Angeles.
Further south, evacuation orders and warnings were in place for remote communities after a wildfire spread quickly through the Cleveland national forest on Saturday.
A firefighter received minor injuries and two structures were destroyed in the 2.3-sq mile Chaparral fire burning along the border of San Diego and Riverside counties, according to the California department of forestry and fire protection. It was 10% contained on Sunday.
The Dixie fire, the second-largest in state history at 1,193 sq miles, was 48% contained in the Sierra-Cascades region about 65 miles north of the Caldor fire. Nearly 700 homes were among almost 1,300 buildings destroyed since early July.
Containment increased to 22% on the 12-day-old French fire, which covered more than 38 sq miles in the southern Sierra Nevada. Crews protected forest homes on the west side of Lake Isabella, a popular recreation area north-east of Bakersfield.
The Department of Defense is sending 200 soldiers from Washington state and equipment including eight C-130 aircraft to help firefighters in northern California. The C-130s have been converted to air tankers that can dump thousands of gallons of water on the flames.