Linda Steadman, 62, was found dead in her home in Larimer County, CNN reported Tuesday.
"Linda Steadman, mother, grandmother, sister and wife perished in the cabin she loved," the family said in a written statement.
The blaze, said to be the third largest in Colorado history, was reported 80 percent contained early Tuesday. More than 500 firefighters battled the flames, and officials said they are aiming for full containment by Tuesday afternoon, the Salt Lake Tribune reported.
The Denver Post reported more than 100 homes have been destroyed.
As of Monday, 2,600 evacuation order notifications were issued but many residents are refusing to leave, KUSA-TV, Denver, said.
Lightning is suspected as the cause of the fire, which started early Saturday.
In New Mexico, firefighters lost ground as the Little Bear Fire in Ruidoso grew to about 38,000 acres as of Tuesday morning, the Ruidoso News reported. The Albuquerque Journal reported Gov. Susana Martinez announced Monday she would declare a state of emergency to boost funding to firefighting efforts. Both newspapers reported 30 percent containment as of Tuesday morning.