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Western Mountaineering SummerLite

rated 4.0 of 5 stars
photo: Western Mountaineering SummerLite 3-season down sleeping bag

I put this bag to the test over 22 days in the High Sierra backcountry. It performed! Warm, comfortable, lightweight: I highly recommend it for your summer adventures.


  • Lightweight
  • Warm
  • Comfortable
  • Durable


  • Down can shift

I really enjoy sleeping in this bag. I would definitely recommend it for a JMT thru hike or for anyone traveling light in the mountains in the summer. It would work well as a winter bag for many low-elevation regions, but is truly a summer only bag for those sleeping above tree line.


I used this bag down into the high 20s on the Tyndall Plateau and was warm with my normal Patagonia Thermal Weight baselayer top and bottom. I custom ordered my SummerLite with a footbox overfill (an additional 1.5 oz of down added in the footbox) because my feet tend to get cold. My feet were never cold in this bag wearing a midweight hiking sock to sleep.

I toss and turn a lot which makes mummy bags tough; but, I like the light weight and thermal efficiency of mummy cuts, so I deal with it. My tossing (I think) led to a cold spot forming, but the material is so light and translucent that seeing where it is and pushing the down around is pretty easy.

The continuous baffle construction, however, offers a double-edged sword: you can shift down to the top of the bag for cold nights and to the bottom of the bag on milder nights, but down can also move on its own. I ended up shifting almost all of the down to the top, and this helped keep me consistently warm.


Fit & Comfort:

The length is true to size — I am 5'8" and the regular length is perfect. The cut of this mummy is pretty narrow, but not confining. I found the fabric very soft and comfortable. After 22 nights, I was still happy to crawl into this bag every night. TRY IT ON IN A SHOP BEFORE YOU BUY!

Side-sleepers: if you sleep on your side in the bag rather than shifting the bag with yourself, you may experience cold spots. Check the shoulder girth if you're ordering without trying on in person (59"-60" for the SummerLite depending on overall size).

Construction & Durability:

This is my third WM bag and for good reason. Western Mountaineering's materials and construction are consistently top-notch. The fabric and stitching held up to 22 nights of use on the trail in Yosemite, Sequoia-Kings Canyon, and the Sierra National Forest this summer. During an afternoon storm, I got into my tent dripping, and the fabric/DWR shed moisture like a dream. The fabric is tightly woven, but never felt clammy, even on mild nights in the 40s.

Packability & Loft:

This bag is pretty lofty, but packs down small. I would set up camp between 4pm and 6pm most nights, take the bag out early, give it a shake, and walk away. When the stars came out, I crawled into a fresh, lofty, warm bag every night. There was no noticeable loss in loft with each subsequent stuffing. Every few days I would lay the bag out in the sun to make sure the down was not retaining excess moisture.

The SummerLite packed easily into a 13L Sea-to-Summit UltraSil Dry Bag with room to spare. I like these because they are fully waterproof and make compression easy without bulky straps.


My SummerLite drying near the Kern River.


This bag is simple. It has a full-length, two-way zipper for custom venting; a full-length draft tube; and a hood drawcord.


Hood and drawcord

Draft tube to seal out the cold

I wish it had an additional draft collar or a face-hole draft tube to seal out cold air, but a hooded baselayer mitigated this. I like that there aren't a bunch of loops, pockets, and extras to weigh it down. 

IMG_4135.jpg     IMG_4136.jpg

Wide hood opening and fully cinched. I still want a draft collar of some kind.

IMG_4131.jpg     IMG_4130.jpg
WM bags come with a nice over-sized cotton storage sack and a durable nylon stuff sack for packing.


I used this bag once in the Ventura County backcountry with lows in the 40s and then for 22 nights on the trail in the High Sierra. Night were mostly in the 30s. Two nights saw temps in the high 20s. Four days saw precipitation, only two of those were considerable. Humidity was mostly low.

P.S. I apologize for my lack of field-use photos. I was too busy being in awe of the natural beauty of the Sierra to shoot too many images of my sleeping bag ;)

Source: bought via a "pro deal"
Price Paid: $235 pro deal


  • Very lighweight for hooded mummy
  • Comfortable at 23-25 degrees
  • Highly compactible


  • Price
  • Doesn’t handle moisture all that well

I have tested WM Summerlite in the Colorado Rockies (say, above 9000 feet), where you can expect frosty nights at any time. I would not recommend to venture out, even in midsummer, with less than a 20°F bag.

BUT 32°F Summerlite did quite well in keeping me comfortable in July. I was dressed very warmly, ofc. (comfortable is the right word here, not warm). I guess this is because of the comtinious baffles; there's an unbroken four-inch layer of down separating the two nylon shell fabrics. This eliminates cold spots and allows the ten ounces of down to work together, minimizing the need for more fill.

This is the most recommended for those worrying more about weight than about budget. (The price is the reason I rated Summerlite 4 out of 5). You can find some cheaper goose down US-made sleeping bags on the market.

While there is no arguing that the Summerlite is pretty supreme in terms of insulation performance and wind blocking, it does have something of a weakness against moisture. While it is true that no down sleeping bag fares well with water, the exterior nylon-based shell of the Summerlite feels a bit more susceptible than other models.

You can read my comparison of ultralight sleeping bags at WildProofGear.

Source: borrowed it

Purchased a Western Mountaineering Summerlite as light bag for backpacking. It is indeed very lightweight and well put together.

But major drawbacks: It is very confining in the torso (I am 5'10", weigh 170) so that my arms only just fit inside. Held up to sunlight the fill is seen to be thin and even missing in places. On two AT backpacking trips of about a week each I was cold at temps in 30-40's, wearing three layers of clothing.

Price Paid: $300

Used this for a month in the woods for military training exercises.


  • Very warm
  • Comfortable enough to move around and curl like baby


  • Moisture gets in
  • Not that waterproof
  • Pretty easy to rip

It's great for sleeping outdoors even if you don't have a cushion or sleeping pad. I got one for a military training exercise since the army ones aren't as comfortable. I didn't mind the price for comfort, however, it doesn't do well in wet conditions. Moisture still seeks in and gets a weird smell. If you're not going to be in a wet area, it's perfect.

The Summerlite rips TOO easily, I found a gap on the back after sleeping on some branches and rocks. Customer service was great about it and is very helpful to deal with.

I usually try them and return them after the field to see which one is the most durable, first handed.


I've been using a bunch of different types of sleeping bags in the last 6 years for the field. Here is the list of sleeping bags I've tried and returned:

Source: bought it new
Price Paid: $410

This is the bag, look no further.


  • Weight
  • Warmth
  • Stuff size
  • Really, you need more?


  • Some will say cost, but wish they had ponied up.

I read the reviews, and knew this was the bag, but I had to be sure I suppose...

I ended up returning the MH Mountain Speed 32 for a really bad zipper design. (Even emailed them about the issue. Honestly, who wants to be out in nature with a stuck zipper? There is no way Ueli Steck actually tried this bag on a summit — he would say the same thing.)

We arrived at the trailhead with frost on the ground and temps somewhere around 30°...  I pitched my tent in shorts and sandals at midnight (it was 70 degrees when we hit the road) and slept like a baby, in nothing.

Drink some cheap bourbon for a week and buy this bag.

Source: bought it new
Price Paid: Retail

I used the bag for the first time backpacking in northern Minnesota in the fall. I decided to bring this bag based on weather forcasts predicting the overnight lows in the mid 40's. The temperature plummeted to the 30's as soon as the sun set, and I wasn't looking forward to testing the bag's rating. By the time I crawled into the bag, my digital temp display was showing 27F. I was expecting to spend a long night shivering in the fetal position. Fortunately, the bag lived up to its rating of 32F, and I didn't get cold during the night. Granted, I wasn't peeling off the layers, but I wasn't cold either.

Pros: conservative temp rating, small pack size and weight.

Cons: none

Temperature Rating: 32


  • VERY lightweight
  • Compacts to the size of a cantalope
  • Comfortable at 23 degrees
  • VERY high quality
  • Love the color


  • Price

Just spent 7 days on the JMT. Every night was at 10.5 to 11.5 thousand feet. Even at 23 degrees (with frost all over the place!) was quite cozy.

I'm 5'9", 170 lbs, a side sleeper and, was quite comfortable with the fit. 

I just can't say enough good things about this bag!

Source: bought it new
Price Paid: $320 (on sale)

The SummerLite is a great summer bag.  It's a little light to be a true three-season bag in Oregon. 

I wrote a detailed review of the bag at

Price Paid: $330 (long)

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short regular long
Price Current Retail: $470.00-$520.00
Historic Range: $252.00-$520.00
Reviewers Paid: $235.00-$410.00
Weight 1 lb 2 oz / 490 g 1 lb 3 oz / 525 g 1 lb 5 oz / 560 g
Fill weight 8 oz / 255 g 9 oz / 275 g 10 oz / 295 g
Loft 4 in / 9.5 cm 4 in / 9.5 cm 4 in / 9.5 cm
Temperature rating 32 F / 0 C 32 F / 0 C 32 F / 0 C
Fill 850 fill-power down 850 fill-power down 850 fill-power down
Shape Mummy Mummy Mummy
Max user height 5 ft 6 in / 165 cm 6 ft 0 in / 180 cm 6 ft 6 in / 200 cm
Shoulder girth 59 in / 152 cm 59 in / 152 cm 60 in / 152 cm
Hip girth 51 in / 130 cm 51 in / 130 cm 52 in / 130 cm
Foot girth 38 in / 97 cm 38 in / 97 cm 38 in / 97 cm
Product Details from Western Mountaineering »