The blaze broke out Monday morning west of Lethbridge, about 200 km south of Calgary, and has put the southern Alberta city on emergency alert.
Officials have ordered the evacuation of some Lethbridge communities, including those east of 30 St., north of Walsh Dr., and the westside trailer court and area.
Evacuees are asked to go to the Enmax Centre or the Fritz Sick Centre.
Residents of Coalhurst have been ordered to evacuate to nearby Picture Butte.
The communities of Indian Battle Heights, Heritage Heights and West Highlands have also been warned they may be evacuated.
People are being asked to avoid affected areas and close doors, windows and vents and prepare for possible evacuation.
Those with breathing difficulties should seek medical attention.
Residents are also being asked to limit cell phone use to keep lines clear for emergency services.