Coldest I ever hunted in was in West Pa near Parker Dam. Father in Law had bought into a Camp there and we went up to hunt for Doe. The Camp had two Electric Heaters and One Deisel Fired Stove and together they barely kept it "warm". Slept in Clothes.
Went to go Hunt and Dad's Truck wouldn't start. Barely turn over. He said let's just go hunt here and we did. I found an old Stand and climbed up to see better. Sat there freezing until 3 Doe cam up by me and I shot 3 times and never hit them standing still. WTH? It must of been so cold the barrel was off, as the Gun was Right On. I gave up and left them walk off.
Got back to Camp and Dad had quit and tried to start the truck. Guy from town below the Mountain came by and drug him up and down the road (Standard Transmission) for about 20 miles before it finally started.
Guy said at his place it as -15 when he left and it was exactly 9 miles from Town straight up the Mountain to where the Camp was. Guy said it was way colder up there, guessed at -20 or -25.
In any case it was dang cold, coldest I ever hunted in.