LOUISVILLE, Colo. — It took only a few hours for the flames to cut an unimaginable path of destruction across the drought-starved neighborhoods between Denver and Boulder.

By Friday morning, as smoke from the most damaging wildfire in state history cleared, more than 500 homes, and possibly as many as 1,000, had been destroyed. Hundreds of people who had hastily fled returned to ruins, everything they owned incinerated in the fast-moving blaze. Entire neighborhoods had been reduced to ashes.

“It felt like the apocalypse,” said Ruthie Werner, a resident of Louisville, Colo., who had gone to shop at a Target store on Thursday but arrived to find the parking lot ablaze.

Despite the astonishing destruction, no deaths were immediately recorded, a figure that Gov. Jared Polis said would be a “New Year’s miracle” if it held.

It turned out that people had just enough time to evacuate, with some grabbing passports and pets, toothbrushes and clothing, as the fast-moving flames, fueled by 110-mile-an-hour winds, leapfrogged highways and strip malls and bore down on their homes.

It “wasn’t a wildfire in the forest; it was a suburban and urban fire,” said Mr. Polis, a Democrat who lives in Boulder County and who described receiving texts and voice mail messages from friends describing what they had lost.

“The Costco we all shop at, the Target we buy our kids’ clothes at — all surrounded and damaged,” he said.

As subdivisions remained blocked off on Friday, the streets empty and hushed as the charred wreckage continued to smolder, residents told of harrowing escapes. In contrast to fires in mountain wilderness, which often burn over the course of weeks, the destruction on Thursday played out in minutes and hours, as fierce wind gusts threw flames across suburban landscapes with virtually no warning.

“We were home, and it was a bright, sunny day, and all of a sudden it wasn’t bright and sunny anymore,” said Laurie Draper, who lost the Louisville house where she had lived with her husband since 1994 and raised two children. “We could smell fire, and then there was smoke coming through the neighborhood.”

Ms. Draper said the wind had been blowing so hard that it was difficult even to open the car doors. They escaped with little more than some Persian rugs, their German shepherd and the clothes they were wearing. On Friday, she lamented that she had not saved items that belonged to her late mother.

“I didn’t take the right things,” she said.

Colorado is no stranger to wildfires, but Thursday’s came at an unseasonable time. Indeed, over the years, wildfires in the American West have been worsening — growing larger, spreading faster and reaching into mountainous elevations that were once too wet and cool to have supported fierce fires. What was once a seasonal phenomenon has become a year-round menace, with fires burning later into the fall and into the winter.

Recent research has suggested that heat and dryness associated with global warming are major reasons for the increasing prevalence of bigger and stronger fires, as rainfall patterns have been disrupted, snow melts earlier and meadows and forests are scorched into kindling.

Peter Goble, a service climatologist at the Colorado Climate Center, said the Boulder region had experienced a wet spring followed by months that were “extremely dry, since about the middle of summer.” He added that “an event like this puts into context how dangerous and how potentially deadly winter season fires that occur primarily over grassland can be.”

As the fire raged and raced toward them, shocked residents of Boulder County desperately tried to save what they could. Liz Burnham, whose apartment in Louisville was narrowly spared by the blaze, grabbed clothes, toiletries, important documents and letters from her mother.

“At a certain point, the smoke became so thick, I couldn’t breathe anymore — I decided to get a bag ready,” Ms. Burnham said. She added: “I have this video of flames right across the street. I just panicked. That freaked me out so badly. I grabbed everything I had packed and my dog, and we just ran to the car.”

Others had no homes to return to and had no opportunity to save their belongings.

David Hayes, the police chief in Louisville, a suburb with about 20,000 residents, lost the four-bedroom house where he had lived for 30 years. When he attended a news conference on Thursday, he did not know the status of his home. He drove by later that night and saw the flames.

“I didn’t want to take advantage of my status, so I didn’t even go up the driveway,” Chief Hayes said. “So, I just watched it burn from there for a little while, and went back to the office. Now, it’s just ashes.”

It had already been a miserable 2021 in Boulder County, marred by a relentless pandemic that is surging again and a mass shooting at a grocery store in March that left 10 people dead. As residents took stock of the fire damage, some expressed a sense of resignation that what had happened on Thursday was a frightening new part of what it means to live in a landscape scarred by the warming earth.

“I’m seeing my future,” said Angelica Kalika, 36, of nearby Broomfield. “I grew up in Colorado, and this is a place where I’ve had snowy Christmases and a nice 60-degree summer. But for me, this is a moment of deep reckoning of climate change when there is a wildfire outside my door.”

Colorado had the three largest wildfires in its history in the summer of 2020, each burning more than 200,000 acres, Mr. Polis said. But those fires burned federally owned forests and land, he said, while the fire on Thursday destroyed suburban developments and shopping plazas.

Boulder County officials said the cause of the fire remained under investigation. Though they initially suspected that downed power lines might have played a role, they said on Friday that there were not any such instances in the area where the fire started.

Whatever the cause, the flames quickly roared across open grasslands toward the tiny century-old mining town of Superior and then burst into the commercial center and pricey subdivisions of adjacent Louisville, a fast-growing city that is a perennial pick on lists of the country’s most livable smaller communities.

“I was thinking, How does this happen, in the suburbs?” said Tamara Anderson, who fled her home in Louisville on Thursday afternoon as firefighters drove down her street yelling for people to get out. “And then I’m like, Oh, yeah, 100-mile-per-hour winds, and it’s been bone dry. And that’s because of climate change.”

Ms. Anderson, who spent Thursday night at a hotel, said that her house had been spared but that three others on her block had been destroyed, part of what officials described as a “mosaic” of destruction.

Flames destroyed some buildings but left others untouched, seemingly at random.

Video published by a local television station showed a cul-de-sac where one house had been destroyed, while the others appeared to be intact. In one neighborhood, a line of about 10 still-smoldering rubble piles was situated next to other houses that appeared to have escaped severe damage.

“I think it’s indicative of our future,” said Laurie Silver, a resident of a nearby suburb who on Friday morning stood near the smoking remnants of her cousin’s townhome in Louisville. “And I don’t know what it’s going to take for people to take it seriously. Maybe, when it directly affects people right where they live.”

Ms. Silver said her cousin had been traveling in Tennessee. His only remaining possessions were what he had packed in his carry-on.

On New Year’s Eve, with the fire mostly contained and an intensifying snowstorm promising to help limit additional damage, displaced residents faced another uncertain night at shelters or in the homes of friends or relatives, some still waiting to learn whether their property had been damaged.

“If our place is smoke damaged, who determines that?” said Ben Sykora, who rushed out of his rental home in Superior, Colo., after grabbing a backup computer hard drive and a couple of changes of clothes. “I don’t want to get thinking too materially, but we’re kind of all waiting, seeing how much is this going to flip our lives upside down. As of right now, we just don’t know.”

Boulder County and surrounding areas on Colorado’s Front Range live with the frequent threat of wildfires, although those concerns have historically been associated more with the summer and autumn months and the forested hillsides west of the cities. Few people were prepared for the sudden onslaught on Thursday.

“You think you’re safe here — these things happen in the mountains,” said Steve Sarin, whose apartment narrowly escaped destruction. “Out here, we think we’re relatively protected from the dangers of wildfires. Yesterday was a big wake-up call.”

Dana Goldstein, Isabella Grullón Paz, Michael Levenson and Alyssa Lukpat contributed reporting.