I grew up in Montana. the coldest I have experienced is
-45 degrees..... when it gets that cold it hurts to breath. your snot from your nose freezes to your face and it is so cold there is no moisture the air.
Spent the weekend once (35+ years ago) at our cabin in Northern Minnesota and it got to -43. The cabin wasn’t insulated at the time. Electric blankets and a pot-belly stove did nothing it seemed. Although we were able to sleep a bit. The frost was almost to the ceiling when we got up!
Now that it is insulated (and small) that pot belly stove can get it too hot!