It seems like it has been around minus 30 C for weeks, and I have been reluctant to go winter hiking and camping except for a couple of day hikes on snowshoes. Cabin fever was starting to rear its head. It was -35 this afternoon and I decided on the spur of the moment to test some gear.
Clothing: (not my regular hiking gear) light wool long johns, cotton polyester pants, cotton t-shirt, polyester pullover, breathable shell, fleece vest, poly insulated inner, leather 'street boots' with thin insulation and thin wool dress sock.
Pad: 7XL Exped down mat
Sleeping bag: 30 year old down rectangular Mount Whitney bag, lots of miles, 4.25 lbs total. No tags with specs - just some nylon tape covering holes.
Location: outside deck with poly-tarp shed to keep out snow.
1. I took a fully inflated Exped outside in the cold. In a couple of minutes the air in the Exped seemed to shrink by half and it sounded and felt like waxed paper. I added more air with the pump/bag by rolling the bag shut rather than pressing it on the floor. It was not 'hard' full.
2. Covered it with the sleeping bag in quilt fashion.
3. Lay on the mat under the quilt for a few minutes - felt a bit cool but not cold. Could probably slept if tired.
1. Put a 16" x 50" foil bubble wrap down centre of mat. (It is used to wrap hot water tanks and pipes. Put a cheap sleeping bag with 1/2" polyfill lined with a mylar space blanket under the down sleeping bag.
2. Lay down for about 30 minutes - didn't feel cool, even with the jacket unzipped. Would have stayed longer but had to pick up some folks downtown.
Conclusion: I would probably feel confident winter camping in a tent or tarp at -25 C with a 7XL Exped and a down sleeping bag. I would probably take take an extra foil bubble wrap or thick foam pad as a precaution. It might make sense to take a pulk or toboggan for the additional weight and bulk.
George - Whitehorse, Yukon