I spent a full winter sleeping on a second story screened porch (it was a private porch off my very small bedroom and I figured that since I didn't mind sleeping in the cold, I might as well save the floor space in my bedroom and move the bed to the porch).

On the very coldest nights I would get out my 10˚F mummy bag, and use a couple blankets on top of that, but I was never uncomfortable, even well below zero (Fahrenheit).

Getting _out_ of bed was pretty miserable at times, but it was only a few steps to the door into the house.