Unseasonably warm temperatures and high winds allowed the Mount Cumnock forest fire to grow by a third during the past week.

“Last Wednesday (Sept. 23) it stayed above 20C overnight and we got quite a bit of fire growth,” said Kim Weir, spokeswoman for the Jasper National Park Firesmart program. “Most of the growth happened in a small valley, but we didn’t see much growth over the weekend.”

Weir said on the 23rd, the fire was 1,000 acres in size. By the 24th, the fire had grown by another 372 ha. One hectare is the equivalent of two football fields, or 10,000 square metres.

Fire crews are monitoring the blaze, and are hopeful it will extinguish itself as cold weather and smaller burn windows arrive. The ability for a fire to grow depends on humidity, temperature and forest conditions, Weir said, noting that the forecast should prevent the fire from growing much more in the autumn.

The park still has plenty of seasonal fire fighters available, who tend to work until the end of October, and natural barriers are keeping the fire from threatening communities.

The fire, which has now consumed 1372 hectares of forest, stretched to Mount Bistre and the Shalebanks notch, entering the west end of the Snake Indian Valley.

Weir said the fire is not threatening structure or roads, and trail closures have been put into place from the Horseshoe meadows to the Snake Indian Valley to the Athabasca River. Several backcountry campsites have been affected, however Weir said the campsites were empty at the time of the closure.

Smoke was visible from Highway 16, and communities downwind such as Hinton, Brule and Folding Mountain may notice more smoke.

A lightning strike ignited the Mount Cumnock fire on Aug. 1, and it has been burning ever since. The fire has grown from 200 ha. on Aug. 23 to 1372. ha.