[2][3] Estimates of the proportion of trees killed by bark beetles in the area the fire made its unprecedented run through were as high as 70 to 90 percent.

It was first detected when an elk hunter noticed a plume of smoke shortly after 12:00 p.m. MDT on Wednesday, October 14, in the wilderness north of Kremmling and reported it to 911.

Based on the location and time of year of the ignition, "it may have been caused by a hunter or a backcountry camper, and possibly by accident," according to a Forest Service press release issued June 3, 2022.

The National Weather Service office in Denver/Boulder began to issue civil emergency messages as the fire neared more populated areas.

In this time the fire grew by more than 6,000 acres (2,400 ha) per hour: the equivalent of 75 standard American football fields every minute.

[9] The fire jumped over the Continental Divide, well above tree line, when embers spotted 1.5 miles (2.4 km) from the head of Tonahutu Creek on the west side of the Front Range and ignited a spot fire in the head of Spruce Creek on the east side.

The spot fire, which established itself on the northwest side of Mount Wuh, quickly grew and threatened Estes Park.

[10][11] Trail Ridge Road through Rocky Mountain National Park became impassable as burned trees fell on the roadway.

[12] Late in the afternoon on Thursday, October 22, a cold frontal passage sharply improved weather conditions on the eastern side of the Continental Divide, subduing the portion of the fire that had led to evacuations in Estes Park earlier in the day.

[13] Fuel treatments like thinning and prescribed burns also aided firefighters in their efforts to stop the fire's progression towards Estes Park, in concert with the better weather conditions.