I've done about -84 F (wind chill) during arctic survival. I have to say the warmth keeping ability of a igloo is phenomenal.
When I went to school in Edmonton as a teen -40 windchill was not a show stopper. Then I would move to Halifax and if it threatened -10 they'd cancel school.
When I went to school in Edmonton as a teen -40 windchill was not a show stopper. Then I would move to Halifax and if it threatened -10 they'd cancel school.