I live in a similar area as the OP. While I don't have an easy answer for them, I do want to say that in Ontario temperatures in winter can reach -20C to -30C easily, with the average being -25C. In Fahrenheit that is -4F to -22F with the average being -13F. Wind chills can often make this feel colder & of course drafts are a bad thing.
OP & baustin, as a friendly reminder please keep in mind this website has people from all areas of the world. Temps, cages, etc may not work for others due to such simple reasons as climate.^^
OP, I would say that anything colder than freezing temps should have access to a heater. In your case, since I know it can get very cold here, I would have a back-up plan for winter. Perhaps an indoor coop/aviary just for them or bring them inside where they can stay warm. Best of luck!