MOJAVE NATIONAL PRESERVE, Calif. >> Crews battled “fire whirls” in California’s Mojave National Preserve this weekend as a massive wildfire crossed into Nevada amid dangerously high temperatures and raging winds.

The York Fire was mapped at roughly 120 square miles (284 square kilometers) on Monday with no containment.

The blaze erupted Friday near the remote Caruthers Canyon area of the vast wildland preserve, crossed the state line into Nevada on Sunday and sent smoke further east into the Las Vegas Valley.

A smoky haze blotted out the sun midday on the Las Vegas Strip and obliterated views of mountains surrounding the city and suburbs. Because of low visibility, the Harry Reid International Airport in Las Vegas reported departure delays of nearly two hours.

A fire whirl — sometimes called a fire tornado — is a “spinning column of fire” that forms when intense heat and turbulent winds combine, according to the National Park Service.

The vortexes — which can be anywhere from a few feet tall to several hundred feet high, with varying rotational speeds — were spotted Sunday on the north end of the York Fire.

“While these can be fascinating to observe they are a very dangerous natural phenomena that can occur during wildfires,” the park service wrote.

The whirls require high temperatures to form. In Searchlight, Nevada — an unincorporated area about 12 miles (19.31 kilometers) from the California border where the fire burned — Monday’s high was 100 degrees Fahrenheit (37.8 Celsius), according to the National Weather Service.

Significant portions of the U.S. population have been subject to extreme heat in recent weeks. Worldwide, July has been so steamy thus far that scientists calculate it will be the hottest month ever recorded and likely the warmest to hit human civilization.

Wind-driven flames 20 feet (6 meters) high in some spots charred tens of thousands of acres of blackbrush scrub, pinyon-juniper woodlands and the famous Joshua trees in the New York Mountains in San Bernardino County.

Ileene Anderson, a senior scientist at the Center for Biological Diversity, said it could take the pinyon-juniper woodlands 200 to 300 years to become “a functional community again,” while the blackbrush scrub and Joshua trees are unlikely to regrow after this catastrophic blaze, which erupted without human intervention.

“It will change the habitat possibly permanently,” Anderson said.

Even more, deer and bighorn sheep could become trapped by the flames, she said. If any manage to survive the blaze, their resources in the newly scorched landscape would be severely limited.

In 2020, the Dome Fire ripped through the preserve, ravaging one of the world’s largest Joshua tree forests. Conservationists, including Anderson, are trying to revitalize the land by planting new trees since the species usually isn’t able to make a comeback naturally after a wildfire.

The desert hasn’t adapted to fires; such blazes are rare because there are few ignition points in the harsh terrain. Generally, most fires in the desert are caused by humans, Anderson said.

The cause of the York Fire remains under investigation, though authorities say it started on private land within the preserve. Other details were not available Monday.

To the southwest, the Bonny Fire burned about 3.6 square miles (9.3 square kilometers) in the rugged hills of Riverside County. The blaze was about 20% contained on Monday.

More than 1,300 people were ordered to evacuate their homes Saturday near the community of Aguanga that is home to horse ranches and wineries.

One firefighter was injured in the blaze.

Gusty winds and the chance of thunderstorms into Tuesday will heighten the risk of renewed growth, the California Department of Forestry and Fire Protection said in a statement.