The Cathedral 1 was declared a top priority nationwide due to its size and the value of homes and structures at risk, said Suzanne Shelp, a Forest Service spokeswoman.
An influx of firefighters and equipment including bulldozers, seven helicopters, four air tankers and a DC-10 jet fire retardant bomber came as crews in Arizona neared containment of a deadly blaze that killed 19 Hotshot firefighters near Yarnell on June 30.
No injuries were reported and no structures burned in the Mount Charleston fire in southern Nevada, which started July 1 on the west side of the mountain near Pahrump and quickly spread east into rugged terrain reachable only on foot. Officials said Monday that some $2.4 million had already been spent fighting the fire.
More than 400 homes in Trout, Kyle, Lee, Harris Springs and Lovell canyons were evacuated during the weekend, along with a Clark County-run youth correctional camp that houses 98 teenagers at a mountain elevation of almost 8,500 feet above sea level. State highways 156 and 157 were closed into the canyons, and evacuation shelters were set up at schools in Las Vegas and Pahrump.
Crews were also working to protect about 100 non-residential structures including barns, sheds and corrals, Nichols said.
Mount Charleston is a popular weekend getaway, where summer temperatures can be 15 to 20 degrees cooler than in Las Vegas, where temperatures have been in the triple digits for more than 10 days.
Daytime high temperatures on the mountain were expected to decrease over the next few days after peaking at 90 degrees on Saturday, but firefighters were hampered by gusty winds and humidity levels in the single digits.
"This fire, these last few days and going forward, is going to depend on the weather," Shelp said.
In northern Nevada, the size of the Bison Fire in the Pine Nut Mountains straddling the Douglas and Lyon county lines was increased from about 14 square miles on Sunday to more than 19 square miles Monday. No injuries were reported and no homes were lost, but officials said several old structures burned in the Slater Mine area.
About 600 firefighters battled winds, low humidity and steep terrain to clear fire breaks through grass, pinyon and juniper. They got help from 19 helicopters and air tankers and four bulldozers.
The Carpenter and Bison fires were each about 15 percent contained, with fire managers expecting crews to spend a week on both fire lines. Both blazes were sparked by lightning.