It depends on the species, a bulb from PNG will absolutely kick the bucket in those temps, but something like the Dendrobium kingi or specisoum will do well outside it frosts. Most of my native orchids are outside. One is in a tree next to the road where it cops all the elements all year round and usually gives about 14 to 20 spikes a year.
So best option is look up to see what part of the world your orchids are from, if it's similar to your climate you should be fine.