Rest well to weather cold days.
» Stay dry. Change into dry layers to sleep, brush off snow before entering your tent, and keep a small sponge on hand to wipe condensation off walls.
» Insulate. Don’t lose heat to the frozen ground. Layer a foam pad under an inflatable, or get a cold-weather pad like Kelty’s Recluse 2.5i ($80; kelty.com).
» Warm up. Pile on calories at dinner and snack before bedtime. For a warming boost snuggle with a hot-water-filled bottle and do a few sit-ups in your bag.
Keep Gear Frost-Free
Don’t lose performance in a deep freeze.
» Boots and gloves Put gloves and shoes and/or boot liners inside a stuffsack and keep the sack in your tent or sleeping bag footbox overnight.
» Water purification Leave pump filters at home; they may freeze and crack. Instead, use a chemical or UV treatment to purify or plan to melt snow for drinking. Note: Boiling water from clean snow isn’t necessary because snow doesn’t harbor gut-busting bacteria.
» Stove Bring a white-gas burner; the fuel performs better than canisters in temps below 40°F. Melting snow to drink? Pack at least 6 ounces of fuel per person, per day. Facing extreme temps? Carrying up to 15 ounces of fuel per person per day may be appropriate.
» Electronics Alkaline cells use water-based electrolytes that freeze at 32°F. Keep cells warm in your pockets or use lithium (which work down to -40°F).