yes, your winters are too cold..too severe.
some people are having good luck keeping VFT's and Sar's outdoors in bogs all winter, in the north, but the bogs are large, IN the ground, and very heavily mulched..it *can* be done, but its very risky..IMO the fridge is much safer, because inside the fridge its just *above* freezing..not far below freezing like outdoors!
yes, the "fridge method" is good for people who have severe winters..
im up in Rochester, NY..where winter is litrerally 5 months long (all of November - March), temps in the 10-30 range for weeks at a time, and massive amounts of snow...its just far too brutal to keep CP's outdoors in those conditions..so the fridge is good.
check out here for details on the fridge method: