I don't actually know how cold out it was, maybe 40 degrees or so. Not too cold considering it was early September, but it was rainy and in the Rocky Mountains so not a warm summer evening for sure. Either way, my face was cold sticking out but every inch of me inside the mummby bag was warm. A good deal for the price. I am a chronically cold person and I actually gave the extra blanket to the dog, so it kept me plenty warm.