What temperature sleeping bag do I need for a summer in the Rockies?

I'm planning a hike of the Colorado Trail starting in July. What's the best temperature sleeping bag to buy, and what bag do you recommend? Robin Dillon, Colorado


That will be a great trip. The Colorado Trail stretches almost 500 miles from Denver to Durango. It winds through the Rocky Mountains in Colorado, traversing six wilderness areas and eight mountain ranges at heights of up to 13,334 feet. In fact, most of the time you’ll be 10,000 feet or higher. That means nights can be chilly, especially if you’re still on the trail after mid-August.

Western Mountaineering Alpinlite Super Sleeping Bag

Alpinlite Super Sleeping Bag

That said, it won’t be frigid. If you’re a cold sleeper, a bag rated to 20 degrees would be more than adequate—warm enough for cold nights, but not so toasty you’ll poach when the temps are higher. At the pricier end for a bag such as this you’ll find Feathered Friends estimable Swallow ($349;, rated to 20 degrees with a water-repellent EPIC shell. It weighs just two pounds and is an excellent bag. Western Mountaineering’s Alpinlite Super ($385; weighs just a touch less than the Swallow and offers a little roomier cut than most mummy bags. For something more affordable, REI’s Sub Kilo +20 bag ( sells for $239 but is on sale now for $160. It uses good-quality down, has an excellent polyester shell, and weighs one pound, thirteen ounces.

Otherwise, a bag rated to around 30 degrees should do nicely. I like Marmot’s Arroyo ($249;, an 800-fill down bag that weighs one pound, eleven ounces, uses Marmot’s excellent silicon-finished nylon shell, and has a snug-fitting hood. Or, Mont-Bell’s U.L.SS. Down Hugger #3 ($270; is a super-light (one pound, seven ounces) bag that uses Mont-Bell’s proprietary stretchy shell to gently “hug" you as you sleep. That helps reduce cooling that occurs when you thrash around and force warm air out of the bag. I’m using this Mont-Bell bag on some trips this spring and really like it. Sierra Designs’ Osage ($179; uses slightly less fluffy down and heavier materials; but the result is a 30-degree bag of reasonable cost that still weighs only two pounds, four ounces.

Note that I’ve mentioned all down-fill bags. For a trip such as yours I think that’s the ideal material;—light and warm. One synthetic option is the North Face Cat’s Meow ($169;, which uses Polarguard Delta fill, has a temp rating of 20 degrees, and weighs two pounds, ten ounces.

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Filed To: Sleeping Bags
Lead Photo: courtesy, Western Mountaineering