Froze in the twenties.
I really like the idea of the insulationless backside and compartments for a sleeping pad, though didn't enjoy this bag. It seems like I'm either too hot or too cold in a sleeping bag. I bought this bag and used it on a trip to Moab, Utah. Temperatures at night were mid twenties, and I froze. The next day I went into town and bought a Western Mountaineering Puma 15 degree bag and was cozy. I've wondered how comfortable this bag would be in warmer weather like 30 plus, but took the bag back so never found out.