The current Bear Archery manual for traditional bows says:
"If you are hunting in cold weather, do not leave your bow outside overnight. If your bow has been exposed to extreme cold, give it a brisk rubdown before flexing."
I hunt and practice with my recurves and R/D longbow in what passes for cold weather here in SE New Hampshire, typically getting no lower than 0 ºF/-18 ºC in the daytime. The decades-old selfbows stay inside when the temperature drops below 25 ºF/-4 ºC.
I have an acquaintance who lives in Alaska and is a member of a trad club up there. I'll ask her what their experience has been and report back.