February 18, 2001


Should you use an air mattress when it's -30 degrees?

Should you use an air mattress when camping in temperatures below -30 degrees? My Sierra Designs Sandman bag is rated to -15 degrees but I was chilly on my Coleman air mattress. What's up.

— Mark Virginia Beach; Virginia

Um, no —- you should not use an air mattress in cold weather or when sleeping on cold ground. When you get in your bag, you already lose some insulation because you crush the down or synthetic fill that's beneath you. You need to make up for that somehow and insulate yourself from the ground—thus the need for an insulated pad. An air mattress, while comfortable, will take on the same temperature as the adjacent air or the ground beneath. In other words, it will be as cold (or colder) than the air outside —- and you won't have any protection against that.

The way to combat that is with a pad that uses closed-cell foam, which creates tiny air pockets, which unlike a single BIG air pocket can help insulate you. The standard, of course, is the Therm-A-Rest pad from Cascade Designs, $65 in the Standard model. But there are options. The Artiach Skin Mat ($72) has a non-slip covering and packs down a bit more neatly than the Therm-A-Rest. There also are several good non-inflating pads out there, such as Mountain Hardwear's Backcountry 72 ($59).

In really cold conditions and when sleeping on snow, it's often a good idea to use two pads. One good combination: A three-quarter length Therm-A-Rest ($50), coupled with an ultralight non-inflatable pad such as Cascade Designs' Z-Rest ($32).