The only thing you really need to worry about is condensation forming.
I shoot all winter long and have yet to experience any kind of trouble. The odd time its been so cold I could the motor grind a bit but no worries. typically Weather conditions for me are anywhere from 0 to minus 25. The odd time Ive been out when it was minus 30.
If you dont have any weather sealing you may want to be a bit careful in snowfalls, but again Ive shot in some heavy falls without batting an eye…Mind you I have weather sealing.
But if you really want some confort look no futher than people who shoot alot in Northern Canada. Quite a few people I “know” have been shooting Owls for a few weeks in minus 30 to minus 40 temps…Or those who venture to places like Churchill Manitoba and James Bay to shoot Polar Bears.