SOUTH LAKE TAHOE, Calif. — It looked like twilight at midday here, then a billow of smoke made the sun vanish entirely on a sharp bend around Inspiration Point. The redwoods and firs, old and graceful and lovely, now resembled nothing so much as fuel for a fire still menacing one of California’s great natural wonders and the people who make a living from it.

The Caldor Fire continued to blaze along the granite ridgeline above this abandoned tourist town on Wednesday, smothering the burger joints, Jet Ski rental shops, margarita havens and million-dollar homes in a thick acrid haze. By midday, the fire had burned through more than 204,000 acres of wilderness and was just 20 percent contained, but it still remained south of here, state authorities said.

Only emergency vehicles remained on the roads of this town of 22,000 people, stunningly quiet and vulnerable. The emptiness before the disaster is a rare sight here. Many recall the aftermath of the Camp Fire three years ago and the mangled city of Paradise it left behind, empty and ruined.

But the wind, blowing for days from the southwest and casting the flames closer to this town and leaving others nearby in embers, has been fickle. A red flag warning — for critical fire weather combining high temperatures, dryness and strong winds — was in place until Wednesday night, but at midday, the air was stagnant, hard to breathe, with no breeze. As the afternoon wore on, the smoky breeze stiffened at upper altitudes.

The fast-moving Caldor Fire moved into South Lake Tahoe, Calif., forcing evacuations and sending residents to evacuation centers in Reno, Nevada. (Erin Patrick O'Connor, James Cornsilk/The Washington Post)

“One moment it’s like this, and within minutes it’s blowing 30 miles an hour,” said a CalFire crew member, outfitting his truck and filling it up with gas before heading toward the hill, clouded behind smoke behind the lake and town.

“The briefing we get each morning is the best they have,” said the firefighter, who spoke on the condition of anonymity because he was not authorized to speak to the media. “But it’s very hard to tell what it’s going to do.”

At that briefing on Wednesday morning, CalFire officials said crews had made progress overnight thanks to weaker winds than they had predicted on Tuesday. The northeastern reach of the fire, close to the homes and businesses in the city of South Lake Tahoe, for now appeared to be protected by a “dozer line,” a type of fire barrier dug by bulldozers, an official told firefighters.

“We lucked out a little bit yesterday with some of the winds that didn’t come up quite as hard as we expected them to,” Tim Ernst, a CalFire operations section chief, said at the briefing. “We’re fortunate the fire did not make as strong a push into Tahoe as it did the previous day.”

But Jim Dudley, a CalFire meteorologist, warned fire crews that conditions remained incredibly dry, and that the winds — still expected to reach 35 to 40 mph — would be “swirly, gusty” throughout Wednesday. “The wind is going to be the main driver of things,” he said.

A new eeriness also settled across the border in Nevada on Wednesday, one day after officials ordered the evacuation of several communities along the eastern side of Lake Tahoe.

Residents of parts of Douglas County, Nev., joined the ranks of tens of thousands of residents and tourists who were told to leave the Tahoe Basin on Monday as the fire crested the Sierra Nevada, tumbling from the western slope toward the lake in its third week of burning. Major casinos in Stateline, on the Nevada side, have shut down gaming.

Firefighters fear that winds will propel the flames toward South Lake Tahoe, which until now has been protected by a massive wall of granite. Erratic gusts could send embers down the cliff, lighting up trees and homes, lodges and restaurants in the Tahoe Basin. On Tuesday, the fire spread from treetop to treetop, lofting embers that were able to ignite new “spot” fires over a mile away.

Jason Hunter, a CalFire spokesman, said that kind of distance is making the blaze very difficult to control.

“We can cut a 10-blade dozer line and are unable to prevent it from spotting over,” he said, standing on a smoke-choked road in the evacuated Pioneer Trail neighborhood between South Lake Tahoe and Meyers. On several occasions, he said, the fire had hopscotched over a half-mile or even a mile, skipping bulldozer lines and igniting green fuels.

Along with the wind, the very dry air associated with this week’s weather pattern is also a concern. Lower humidity allows fine vegetation beneath the forest, like grasses and leaves, to remain extremely flammable, which enhances fire spread. That is a volatile mix when combined with forests that are parched from summer heat and drought.

As of Tuesday evening, firefighters had built bulldozer and fire line around homes in the Pioneer Trail area of South Lake Tahoe, behind hundreds of houses leading to a ridge where the fire was actively burning. Engine crews scanned neighborhoods below the hill for spot fires. Every so often on the radio they would call out “Spot fire!” and run to extinguish the flames.

Along Oneidas Street, the El Dorado Hotshots were working with bulldozers to cut fire line up the hill from those homes city engines were protecting. The Hotshots are an elite U.S. Forest Service firefighting crew based in Pollock Pine near Placerville. They had worked the week before to defend their own base and neighborhoods; now they were farther east in the Tahoe Basin, fighting to save an area where they and their families recreate.

“The fire environment is drier, it’s hotter, the fuels are much drier … we’re seeing rapid fire growth,” crew superintendent Ben Strahan said of the conditions they were facing. “You think you got a handle on what’s happening, then the fire goes two to three miles on the next shift.”

Local fire officials in the Lake Tahoe area reported what they called “an alarming trend” — evacuated homeowners leaving behind running sprinklers and hoses, some on rooftops, in apparent attempts to safeguard houses from the approaching fire. Those efforts do not protect structures, the North Tahoe fire officials said, and in fact are drawing down neighborhood water tanks and wells, robbing supply from fire hydrants and the firefighters who use them to defend the homes.

Residents should instead remove combustible material from areas around houses — clearing pine needles from roofs and decks, and furniture from porches, officials said. “Hardening homes to ember intrusion is one of the most effective preparedness efforts residents can take to protect their homes in a wildfire,” North Tahoe Fire Chief Steve Leighton said in a statement.

History is in peril here, some already gone. The road to Lake Tahoe skirts the Donner Pass and passes offramps for Gold Run and Secret Town, the evocative remnant of this region’s Gold Country Past. Grizzly Flats, not far from here, was badly damaged by the Caldor Fire. At an event in Oakland on Tuesday, Gov. Gavin Newsom (D) referred to the town as “history, traditions, memories.”

“All of this is at risk,” Newsom said. “But we must remain a leader on climate change.”

Newsom repeated the message here Wednesday that California’s several-year run of historic fires is the direct result of its shifting climate, one of extremes — from drought to floods, temperatures near freezing in the back country one week and at record highs the next.

Much of what is burning is federally managed, which accounts for 57 percent of California forest land. Newsom said the state had invested $2 billion in recent budgets to prepare against fire, a record amount, and that more than 4,000 firefighters were on the ground now.

Although 26 helicopters and larger fixed-wing planes have been active in the operations, the sky was largely quiet over South Lake Tahoe on Wednesday, visibility so poor the cobalt blue of the lake could not be seen from just blocks away.

The main stretch is lined with shuttered Chinese restaurants and burrito places, inns and lodges losing peak season revenue. The Tahoe Valley Motel left the word “Sorry,” lit in red neon that was visible through the smoke, but its “No Vacancy” message remained unlit.

Diana Leonard contributed to this report