The Fern Lake fire, burning in Rocky Mountain National Park since Oct. 9, more than tripled in size overnight, forcing the evacuation of 583 homes early Saturday.
The 4,400-acre fire, sparked by an illegal campfire in Rocky Mountain National Park, exploded early Saturday when it was pushed by strong winds, with gusts up to 75 mph.
"The wind last night was very strong and fanned the flames," said John Schulz, spokesman for the Larimer County Sheriff's Department. "It jumped the lines."
An unoccupied, privately owned cabin was destroyed, and many others were threatened, Schulz said.
Fire spokeswoman Traci Weaver said teams made good progress fighting the fire Saturday, but high winds were expected again Sunday, especially late in the day.
A Type I incident management team will assume control of the fire Sunday.
"What we really need is snow," Weaver said.
Snow, however, is not in the forecast. A cold front Sunday was expected to bring more gusts but not much moisture.
Before Friday night, the fire had been listed as 1,515 acres in steep, rough terrain. Containment had been up to 40 percent. Weaver said she could not estimate the level of containment Saturday.
For most of November, the fire smoldered quietly, being monitored by about a dozen firefighters, with containment expected by Dec. 17. Suppressing the fire on the ground was considered extremely unsafe because of the terrain, and officials expected the fire to diminish once the snows came.
An evacuation center has been set up at Estes Park High School. The Salvation Army and Red Cross are providing meals for the evacuees.
Large animals were being taken to the Stanley Park Fairgrounds, 1209 Manford Ave.
Support to fight the fire increased from 61 firefighters Friday to 200 Saturday. Two hot-shot crews were on their way to the wildfire, and numerous local fire engines were headed to the area, officials said.
The arrival of two heavy air tankers from Southern California was delayed at least one day because of poor visibility in the area, Patterson said.