Blaze is in a steep valley about 10 kilometres northwest of the Sunshine Village ski area
Crews continue to battle a wildfire in the Verdant Creek area west of Calgary, which has forced the closure of parts of Banff and Kootenay National Parks.
Officials said it grew in size overnight but conditions were too smoky on Sunday to estimate its size.
"It's a very narrow valley with very steep terrain so it's not safe at this time to put crews on the ground," said Jane Park, incident commander for the fire.
"We've primarily been actioning the fire through bucketing with helicopter resources. We've managed to work on some of the flanks we're trying to keep from spreading … but it's fairly difficult with these conditions and the wind we're experiencing right now."
Several popular hiking trails in Banff and Kootenay National Parks are closed until at least Tuesday and backcountry reservations have been cancelled because of the fire.