The Western Mountaineering SummerLite is the lightest fully baffled sleeping bag that Western Mountaineering makes. It's perfect for any adventure where weight and pack space are at a premium, though it is not comfort focused. It's designed to be as light and compressible as possible but doesn't sacrifice warmth or functionality. It shaves ounces by offering slim, thermally efficient dimensions, and a simple, but still very functional hood. It's sewn in San Jose, California with top-shelf fabrics and the highest quality 850+ goose down available. For more casual all-around applications, this bag is okay; but where it really excels is during long-range missions or summer alpine climbing where every ounce matters. This bag's warmth to weight ratio is tough to beat.
Western Mountaineering SummerLite 32 Review
Compare prices at 3 resellers Pros: Lightweight, warmer than other 30F models, extremely compressible, fantastic feeling interior fabric, Made in the USA, zipper snags less frequently than other ultralight models
Cons: Tighter than average interior dimensions, included stuff sack could offer better compression
Manufacturer: Western Mountaineering
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Our Analysis and Test Results
The Western Mountaineering SummerLite isn't necessarily an all-purpose bag, at least in the traditional sense. However, its low weight and miniscule packed volume, coupled with an excellent 32F temperature rating, (it proved warmer than several 30F models we tested) make it perfect for those users seeking the most serviceable option for the least weight. This function first design won't win the casual crowd with its ability to accommodate high-knee sleepers, but it will impress anyone looking for the lightest sleeping bag they can get that won't leave them cold when the temperature starts to dip below freezing.
This model uses nine ounces of the highest quality 850 down available. As a whole, our testers feel this bag is warmer-than-average for 32°F rating and in line with many 30F models. This model's nine ounces are slightly more than the similar rated Marmot Phase 30, which uses 8.5 ounces; while 0.5 ounces doesn't sound like much (even to us) in real-world testing, we found the Summerlite to be marginally warmer than the Phase 30. It wasn't as warm as the Phantom Spark 28 nor the Western Mountaineering MegaLite.
We used this bag several times with overnight temps around 35°F and only wore a base layer. Its dimensions are on the tighter-side (and thus, thermally efficient) but not so tight that it wasn't still possible to wear a thin puffy to bed.
The Summerlite's dimensions are thermally efficient and snug at 59"/51"/38" (inches). Those dimensions are in line with other performance-oriented mummy bags in the shoulders but certainly among the slimmest models in the hips and foot area.
We love the feel of the internal fabric, which overall was one of our testers' favorite for how cozy it felt against our skin. We also appreciated how quickly it heated up and it was one of the least clammy feeling of any bag in our review.
The Summerlite isn't SUPER snug but is ever-so-slightly on the tighter side, even compared to other performance cut models. If you're used to performance-cut bags, this model won't feel much different. It's as slim as the Sea-to-Summit Spark III, is close to the Phantom Spark 28, and ever-so-slightly slimmer than the Marmot Phase 30. If you like the weight of this bag but wish it had a little more room, we'd recommend the Western Mountaineering MegaLite, a 30F model that isn't too far off in weight but has far more roomy dimensions.
At a touch under 1 lb. 2.5 oz. (18.5 ounces / 1.15 lbs/ 540 g), this is among the lightest models we tested, and it offers very impressive warmth for its weight. It's literally half the weight of bags that are equal to it in warmth.
In fact, the only model that we reviewed that was lighter was Marmot Phase 30 (1.1 lbs) which offered similar materials, fill amounts, and dimensions. The Summerlite is warmer than the Patagonia 850 down 30, though the Patagonia model is roomier.
The SummerLite is super lightweight but doesn't give up much for warmth or overall functionality. It uses a 12D shell fabric which is thin, but not the thinnest, as the Marmot Phase and Mountain Hardwear Phantom Spark both use 10D. We can attest to using several Western Mountaineering bags for 500+ nights, and they are still holding up well. The bottom line is its hard to find a bag that packs this much warm into a model that weighs as little as this one.
The Summerlite is easily among the tightest packing models available and compressed the smallest of any bag we tested, with the only comparable model being the Marmot Phase. The SummerLite packed around 15-20% smaller than models like the Western Mountaineering MegaLite, Mountain Hardwear Phantom Spark, or Patagonia 850 Down 30.
The SummerLite comes with an included XXS stuff sack that is well sized and struck a balance of being tight (not to mention light at 0.9 ounces) but still very reasonable to pack. With that said, you can still compress this bag to roughly half the size with an aftermarket compression sack.
This bag is perfect for any trip where weight and pack space are at a premium, as long as it isn't too cold. However, its slim dimensions make it less desirable for front-country camping.
Even with its slightly slimmer than-average-dimensions, tester Ian Nicholson (a pretty broad shoulder user) was able to comfortably wear a light insulated jacket in this bag in temperatures down to 24F. Unlike a lot of other sleeping bags in its weight range, the SummerLite has a full-length zipper that extends to within only a few inches of the foot box, which makes opening this bag up (to use as a quilt on those 58F nights) easy and practical.
Features & Design
The SummerLite is a minimally focused bag, with nearly every attribute of its design geared toward obtaining low weight and packability, without sacrificing much, if any, warmth. For example, its dimensions are slim but mostly to be warm.
The SummerLite is Western Mountaineering's lightest weight baffled sleeping bag (versus a sewn through design which isn't nearly as warm and often has "cold spots"). The SummerLite's hood is basic but still useful and comfortable.
Two small features that we liked about this bag are its draft tube, which runs along the length of the zipper, and a stiffer piece of fabric which reduced the number of times the larger-than-average gauge zipper snagged the fabric. Not only did this make zipping and unzipping the bag less annoying, but it helps increase the longevity of the bag over the long term (there are only so many times you can snag the zipper before you manage to rip the fabric). Overall, this model's zipper snagged a lot less than the Marmot Phase or Mountain Hardwear Phantom Spark 28.
The SummerLite is one of the warmest bags you can get for its weight, which equates to countless applications for any trip where low weight and a minimal packed size are of the utmost importance. We use it for dozens of summer alpine climbing trips in the Cascades, Sierra, and Tetons and think its perfect for a majority of 3-season backpacking trips - as long as you don't push it too far into the shoulder seasons. Its low weight and tiny packed size make it perfect for long-range backpacking trips, but it could still easily be appreciated for single night adventures. If you are mainly going to be car camping, we'd buy a different bag, like the slightly heavier but far roomier MegaLite.
At $425, the SummerLite is in line with other high-end performance oriented down bags with similar temperature ratings, using similar materials and down quality. It's very similar in price to the Marmot Phase 30, the Mountain Hardwear Phantom Spark 28, and the Patagonia 850 Down 30.
Like those other bags, the SummerLite uses only the best fabrics and down; however, what really adds to its value is it's the same price but 100% sewn in the USA. Like all Western Mountaineering bags, the SummerLite is 100% built in San Jose, California (where they have to be manufacturing bags for over 30 years). What's not to like about that?
If low weight and a tiny compressed volume are two of your most important factors in your latest sleeping bag purchase, the SummerLite should be at the top of your list. It will last for decades of use and is in line with other performance-oriented mummy bags. Its dimensions are slim, but close enough to other high-end models that the 1-2" diameter difference shouldn't be a significant factor against purchasing it. For summer-alpine climbing or long-range backpacking, there are few sleeping bags we'd rather have.
Other Versions and Accessories
The Summerlite is available in three lengths: Short 5'6ʺ, Standard 6'0ʺ, Long 6'6ʺ.
— Ian Nicholson