Originally Posted by WetRivrRat
I've used a ThermaRest and a TNF Cat's Meow down to the mid-upper 30's in a HH classic entry(bottom) and was almost too warm, not warm enough to vent, but warm enough that it could have gotten colder and still been fine
Used the same setup in the high 40s at 5000 feet during a windy, misty, damp night. Sweated my back off on that thermarest... Wound up leaving sleeping bag open from the waist up, with a light fleece blanket on top of me (I use it as a bag liner because it feels better than the nylon) I have no doubt with the thermarest I could have gone much colder with that setup, especially with the bag zipped up and the liner inside. I had the rainfly flaps closed in tight, which was a problem with condensation, but it was so moist outside, EVERYTHING was wet in the morning. Water condensed on the trees and rained down on me all night. But it sure beat the 95 degree weather down at 500 feet...