SOUTH LAKE TAHOE, Calif. • Ash rained down on Lake Tahoe on Tuesday and thick yellow smoke blotted out views of the mountains rimming its pristine blue waters as a massive wildfire threatened the alpine vacation spot on the California-Nevada state line.

Tourists ducked into cafes, outdoor gear shops and casinos on Lake Tahoe Boulevard for a respite from hazardous air coming from an erratic blaze less than 20 miles away.

The Caldor fire erupted over the course of a week into the nation’s No. 1 firefighting priority and was “knocking on the door” of Tahoe, said Thom Porter, California’s state fire chief. A major wildfire has not penetrated the Lake Tahoe Basin since 2007.

Tourists typically come to swim and hike, relax along the lake’s calm shores or take their chances gambling, not risk their lives in the face of a potential disaster.

Although there were no evacuations ordered and Porter said he didn’t think the fire would reach the lake, it was impossible to ignore the blanket of haze so thick and vast that it closed schools for a second day in Reno, Nev., which is about 60 miles from the fire.

Visitors wore masks outdoors — not because the coronavirus pandemic, but because of the toxic air and inescapable stench of fire. The gondola that ferries summer passengers to the summit of the Heavenly Mountain ski area was closed until winter due to the wildfire risk.

Cindy Osterloh, whose husband pushed a relative in a wheelchair beneath the idled cables, said she and family members visiting from San Diego were all on allergy medications to take the sting out of their eyes and keep their noses from running so they can ride out the smoke for the rest of their vacation.

“We got up and it was a lot clearer this morning. We went for a walk and then we came back and now it’s coming in again,” she said of the smoke. “We’re going to go and see a movie and hopefully it clears up enough that we can go do our boat rides.”

Firefighters worked to contain the blaze, which has spread explosively in a manner witnessed in the past two years during extreme drought. Climate change has made the West warmer and drier in the past 30 years and will continue to make the weather more extreme and wildfires more destructive, according to scientists.

Massive plumes have erupted in flames, burning embers carried by gusts have skipped miles ahead of fire lines, and fires that typically die down at night have made long runs in the dark.

A Croman Sikorsky S-61A helicopter drops water Tuesday on the south end of the Caldor fire near Grizzly Flat Road west of Grizzly Flats, Calif.

Sacrmento bee via AP