The High Park fire, triggered by lightning June 3, has consumed an estimated 87,250 acres, making it the most destructive in Colorado history, and is 55 percent contained, fire officials told The Denver Post. At least 257 homes have been destroyed by the blaze, which killed one person near its start.
The Post said licensed river guides were ferrying crews on the northern end into otherwise inaccessible areas for mop-up operations.
More than 6,000 people have been evacuated near Pikes Peak, where more than 4,500 acres have been charred.
The Waldo Canyon fire was within a half-dozen miles of the U.S. Air Force Academy, immediately north of Colorado Springs.
"I saw a lot of glow in the Air Force Academy area," Colorado Springs Fire Department spokeswoman Sunny Smaldino told The (Colorado Springs) Gazette Monday night.
The voracious fire's giant flames -- which forced evacuations of the Cascade, Green Mountain Falls and Chipita Park communities near 14,115-foot Pikes Peak in the Front Range of the Rocky Mountains -- were fueled by a triple-digit four-day heat wave, relative-humidity levels near zero and sustained hot winds of 10 mph to 20 mph and gusts of up to 35 mph, the National Weather Service said.
This combination will create "explosive fire growth potential," the service said, as it also issued a red flag warning of imminent fire danger for most of the state through 9 p.m. MDT (11 p.m. EDT) Tuesday.
Gov. John Hickenlooper issued a statewide ban on open burning and a ban on personal fireworks ahead of next week's Fourth of July holiday.
Temperatures were forecast to reach 100 degrees again Tuesday and remain in the upper 90s during the day through Saturday, AccuWeather forecast.
Lightning strikes were forecast in tinder-dry areas, the weather service said.
Rain was not due until July 4 or 5.
About 600 firefighters battled the Waldo Canyon fire -- one of a half-dozen large fires burning across the state's dry terrain in the worst wildfire season in a decade.
The Waldo Canyon fire, which started Saturday, is 5 percent contained.
Wildfires are burning in much of the West.
In southwestern New Mexico, the largest wildfire in state history has burned about 300,000 acres.