Heavy rain was in the forecast after a long spell of dry weather that fueled the Waldo Canyon blaze west of Colorado Springs, The Denver Post reported. Flash flood warnings were posted.
Fire agencies warned the combination of rain and burned-over mountainsides could lead to landslides.
The Waldo Canyon fire, which began June 23, spread over 18,000 acres, killing two people and burning 346 homes. By early Saturday, the fire was reported 98 percent contained, and firefighters' main concern was dousing hot spots.
Jack Horner, a fire spokesman, said emergency workers have also turned to measures aimed at preventing or reducing the damage from floods and landslides. These include planting grass on sloping areas and constructing water channels from logs, long rolls of hay and bulldozed earth.