2 little tricks I've learn is, u can go with a little warmer bad ,by 1 going to an army surplus and getting a camo poncho liner very warm and light ,2 is go to ur locale hardware store and buy a 6' piece of hot water heater wrap the silver stuff ,once again very light, put our good ground pad down ,then the hot water reflector then ur bag this does a great job of reflecting ur body heat back at u, and then if It's really cold u have the poncho line to put in the bag with u