Summer Sleeping Bags Review

How the warm-weather down mummy bags Marmot Atom, Montbell Super Stretch Down Hugger #3, Mountain Hardwear Phantom 32, and Feathered Friends Osprey stack up.


Marmot Atom

This warm bag passes muster even on nights below its rating.

Rarely do we find a 40°F bag that's toasty into the mid-30s, but this ultralight, 900-fill down mummy passed that test from Washington's Glacier Peak Wilderness to Alaska's Revelation Mountains. And yet it packs smaller than the other three bags and weighs barely more than a pound. That's because Marmot uses the highest quality feathers available, which translates to high loft and heat-trapping with little weight and bulk. Dimensions are comfortable for someone of average build or smaller--just right in the shoulders and waist, with a little extra thrashing room in the footbox. The Pertex Quantum shell breathes nicely while repelling condensation; the bag also features a locking zipper, draft tube, and nicely fitted hood. Only caveat: The short, 38-inch zipper saves weight, but limits venting on warm nights. $249 (regular, 72 in.), $269 (long, 78-in.); 1 lb. 2 oz. (707) 544-4590;


Montbell Super Stretch Down Hugger #3

Tall, short, wide, thin--this stretchy sack fits everyone.

Tired of sleeping bags that are either too cramped or so voluminous you can't heat them up? We have three words for you: stretch-baffle stitching. Montbell's elastic seams allow this 32°F mummy to expand and contract whenever your body does, meaning you stay both comfortable and warm all night long. At the shoulders, there's a whopping 17 inches of stretch, enough for our broadest big-guy tester. A footbox drawcord also effectively closes off a portion of the bottom of the bag, resulting in a thermally efficient space for shorter adults or growing kids. Warmth is true to the rating and good for the weight, thanks to 725-fill down, a draft tube, and a hood that both adjusts easily and closes up snugly. As a result, I slept soundly through nights in the high 30s in Washington's Olympic Mountains. $260 (regular, 70 in.), $280 (long, 76 in.); 1 lb. 8 oz. (877) 666-8255.


Mountain Hardwear Phantom 32

If the mercury plummets unexpectedly, this bag will rise to the occasion.

If you need a lightweight summer bag capable of carrying you into the shoulder seasons, look no further than this 32°F model. Over five November nights in the Southwest, with lows down to the high 20s, I was warm enough inside while only wearing a single thermal layer and a hat. Part of the credit goes to the efficient cut, which runs just on the comfortable side of snug. And part goes to a generous helping of 800-fill down, which lofts high but packs breadloaf-small. A two-way, 3/4-length zipper helps ventilate on balmy nights, while the 15-denier nylon shell repels light condensation. The Phantom comes in two men's lengths (78 and 84 inches), and a women's version that's 3 ounces lighter, narrower in the shoulders and footbox, and available in two lengths (70 and 76 inches). $245 (all sizes); 1 lb. 7 oz. (800) 953-8375;


Feathered Friends Osprey

With loads of fabric and fit options, you can build yourself the ideal bag.

When you're dropping serious green for a bag, is it too much to expect perfection? You might find it here, because this 30°F mummy comes in 8 lengths (4 men's and 4 women's), with optional custom-fitting. That translates to more sleeping comfort--if you choose extra girth or length. Or more warmth--if you choose the kind of streamlined, body-hugging cut that improves thermal efficiency. Mine kept me warm on freezing nights in Idaho's Sawtooth Wilderness. I also chose the optional waterproof Epic by Nextec shell, which kept the 850-fill down bone dry despite heavy condensation; it does add weight and bulk, though, and slightly compromises breathability. Options include a full or half-length zipper and three additional shell fabrics: waterproof/breathable eVent (more breathable than Epic in our testing, but $35 more expensive), Pertex Quantum (shaves 3 ounces), and nylon taffeta ($50 cheaper than Epic). $315 (as tested); 1 lb. 13 oz. (206) 292-6292;