All three provinces are in the grip of wind chill warnings, with the extreme range hitting -50 C in some areas.
About 400 people in Calgary were suddenly exposed to the extreme cold overnight when a carbon monoxide leak forced them from their central area highrise.
No one was hurt and buses were brought to the scene to keep the evacuees warm while their building was cleared.
Drivers everywhere are being urged to be prepared for the bone-chilling cold in case of stalls and medical authorities are warning about the quick onset of frostbite if skin is exposed for short periods of time.
Environment Canada says there may be some relief from the deep freeze by this weekend when daytime highs start slipping above -20, but breezy conditions will keep wind chills high. (CJME, CHED, CTV Edm)