So the outside temp went down to 47° F the night I used this and I had another extra blanket on top of me too, but as long as I stayed down in this I was okay warm, also with leggings and a sweatshirt on, but I haven't been in a sleeping bag in years and I was just surprised how narrow it is. I'm a woman who wears a size 14, and I just felt tight inside of it, like I could turn on my side but I couldn't really move my arms or legs around. But for $27 it was reasonably warm and it would be okay fSee full review