Western Mountaineering SummerLite Sleeping Bag: Sleeping Right and Light on Summer Adventures

Whether you are looking to gain some backpacking experience or you are a seasoned thru-hiker, the thrill of the outdoors is an incomparable feeling. When it comes to enjoying a night out under the stars or the safety of your tent, your sleep system is just as important as the clothes you wear. Ultralight or lightweight sleeping bags can come as a hefty investment.

As outdoor enthusiasts ourselves, we understand how essential it is to find the best gear while staying within your budget. Today, we will review the Western Mountaineering SummerLite sleeping bag in the hope that its performance, versatility, and value will give you a much clearer idea of the type of sleep system you need while remaining loyal to your wallet.

Product Specifications

  • Insulated draft tube protects you from cold air interrupting your precious slumber
  • 5 1/4″ Spacing/Continuous Baffles that encircle the bag from zipper to zipper
  • 10 oz of down fill with 850 fill power
  • A narrow cut of 59/38″ Shoulder/Foot girth maximizes heat efficiency
  • 1 lb 3 oz total weight makes this Western Mountaineering’s lightest bag with continuous baffles
  • Extra space at the foot bed

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Choosing the best sleep system for your style of hiking depends upon several key factors. Your primary concerns should pertain to temperature rating and warmth expectations. Sleeping bags feature numerous insulation types, but down is beloved for being so light and easy to compress for a smaller pack size.

Western Mountaineering’s three-season sleeping bag is designed for ultralight hikers and thru-hikers that rely on trimming weight where it matters most.

SummerLite Review and Specifications

As with any products we review, it is absolutely essential to cover the most important features so you know exactly how to frame your research to make the most meaningful investment. We have confidently narrowed down some of the most notable features to consider before making your final decision.

Packaging and Packability

Although the SummerLite is not the lightest three-season mummy bag on the market, it packs down well and would be a premium choice for any backpacker or thru-hiker torn between weight and space. Each sleeping bag includes a stuff sack that weights approximately 0.9 ounces and measures approximately six by 11 inches when packed.

From the short to long sizes, the SummerLite weighs between 1.2 and 1.5 pounds. Lightening your load on the trail is easier than you may think. Weighing the gear you plan to take can help you gradually decrease your base weight before adding consumables such as food, water, or fuel. Ultralight backpackers can all agree that down insulation is the preferred choice when it comes to sleeping bags, because it is more compressible than synthetic fill.

Design and Durability

Looking for a sleek bag that is lightweight and rated for colder hikes when your rest really counts? The SummerLite by Western Mountaineering is the ultimate bag for campers who love traveling light on their feet, though it is not the lightest option available.

Most thru-hikers, backpackers, and mountaineers who venture on multi-day excursions avoid adding to their base weight to avoid stress-related injuries or exhaustion from disproportionate strength-to-weight ratio.

One of the greatest advantages to choosing the SummerLite is that you can select your preferred hand orientation, right zipper or left zipper. Although this option may not seem significant, you will want to consider the way you normally sleep and whether you would prefer to reach across your body to unzip your sleeping bag.

Size and Shape

The SummerLite is available in small, medium and large sizes, measuring between 5’6” and 6’6” to accommodate a wide range of body types and sizes. One of the major drawbacks of the fixed girth is that it makes it tough for all but thin hikers to add warm clothing for chilly nights.

This bag features a mummy cut design for maximum heat efficiency. Depending on your height and the size you choose, this bag offers a little extra space at the foot bed that you can use to stow clothing or other backpacking accessories. The narrow design of this bag would be best suited to thin- or medium-sized hikers. Larger backpackers may find this choice too restricting, especially when it comes to wearing extra clothing for warmth.


The ultra-lightweight construction is made from Extreme Lite™ proprietary fabric with an extremely high thread count. The only drawback to this construction is that is sacrifices some breathability to reduce down leakage.

As with any of their mummy sleeping bags, the inner shell fabric is cut narrower than the outer shell to create a differential, eliminating extra interior fabric could lead to cold spots and promoting proper lofting to protect against down compression.


Made in San Jose, California, the SummerLite offers down sourced ethically from free-range geese on an Eastern European farm where they are raised for breeding as opposed to poultry and who are never live-plucked or force-fed. The plumage is gathered from their nesting area while they feed and roam. Depending on the size you choose, each bag features between eight and 10 ounces of down fill and four inches of loft.

The sleeping bag comes with 850+ down that provides exceptional insulation and excels in cold, dry conditions or where saving weight and space are paramount. The down that Western Mountaineering uses in each of their sleeping bags is designed to last at least a quarter or half a century.

Temperature Rating

Rated to keep you cozy in temperatures as low as 32º F, this sleeping bag should serve you well in any weather condition above freezing. Some hikers may find the combination of down with a mummy cut to be overkill for warm summer nights or even nights that never dip below 50º F, but this sleeping bag serves just as well as a blanket or base to rest upon.

Water Resistance

Modern sleeping bags with down are typically treated at a microscopic level with a durable water-repellent (DWR) finish or water-resistant application. Western Mountaineering is in the process of conducting their own long term tests on goose down that has been treated, but they purely rely on the quality and craftsmanship found in each bag they produce.

Unique Features

The SummerLite is unlike many of the ultralight sleeping bags on the market because it offers a unique combination of features. The reverse differential hood is cut with a larger piece of fabric than the exterior, creating a loose down filled fabric that surrounds your head for superior comfort the whole night through.

You can enjoy warm insulation around your head and face without needing to cinch the hood tight, but each bag features a draw cord with a free-floating cord lock that allows campers and hikers to make a quick exit under any circumstance.

Better yet, this mummy bag features a full-length #5 YKK zipper that allows you to open it down to the footbox on warm summer nights. The insulated draft tube prevents warmth from escaping between the zipper coils. Continuous baffles are a delightful feature that most extreme outdoorsmen will appreciate.

The fully-baffled construction encircles the bag from zipper to zipper, allowing you to shift the down insulation from one side of the bag to the other depending on the temperature and your required warmth. The baffles are spaced approximately 5.25 inches apart for seamless coverage.

Value Verdict

Compared to competing three-season sleeping bags, the SummerLite offers a tremendous value for side sleepers and backpackers who tend to sleep in contorted positions.

Your safety is nothing to take lightly and achieving comfort in sinking temperatures is a feat that experienced hikers are all too familiar with. Western Mountaineering is notorious for creating high-quality products that should last you several thousands of miles on trails or in unchartered territories.

Although this sleeping bag does not feature a traditional water-repellant or resistant coating, the differential shell construction provides plenty of protection against most elements. In rainy or extremely wet conditions, you run the risk of your down losing loft. As a precaution, you may decide to pack synthetic pants or a coverup to keep you dry.

We would also advise researching sleeping bag liners to determine whether that added investment would be worth your comfort in colder months or at high elevations.

Related Products

Finding the perfect sleeping bag can be challenging. That is precisely why we strive to point out sleeping bags that can match the SummerLite in most conditions, so you can find the key features that are of most value to you and your hiking or camping style.

Comparable in price, seasonal rating, fill power, and design components, each of these sleeping bags is best suited for specific applications. Explore the advantages and disadvantages to these high-quality sleep system alternatives made by Sea to Summit, Western Mountaineering, and Chinook.

Sea to Summit Spark SP II Sleeping Bag

The Sea to Summit Spark SP II Sleeping Bag is designed to be as light and as minimalistic as possible. With 850+ down fill and a slim design, deciding between this bag and the SummerLite may prove challenging, but there are certain differences that may make your decision a little easier. Users who were either size or weight conscious were very pleased with this sleeping bag.

Not only is it much warmer than most minimalist bags, but it also includes an Ultra-Sil compression sack, mesh storage cell, and laundry bag that enable the user to pack it down to a small size comparable to a football and maintain it for lasting quality.

Common grievances pertain to the 1/3-length zipper that was implemented to save weight over a full-length zipper but ultimately limits this bag’s versatility, making it harder to get into the bag. The lack of neck baffles or a collar can also leave you vulnerable to drafts and allow heat to escape. However, the Spark SP II’s ultralight 10-denier nylon shell is treated with a DWR finish to shed moisture and may perform better in wet conditions.

The Spark SP II offers an excellent value for hikers looking to get outside this summer for mountain excursions, cycle touring, ultra-light hiking, or adventure racing.

Although Sea to Summit claims that this bag is ideal for spring, summer, and mild winter adventures, we would recommend investing in a liner to keep you extra toasty on those chilly nights. Otherwise, the SummerLite is a more versatile sleeping bag that will keep you warm.

Western Mountaineering UltraLite Mummy

The UltraLite Mummy sleeping bag is a fine alternative to the SummerLite and features many of the same useful design features that Western Mountaineering is known for.

This slightly advanced counterpart features the same full-length zipper, continuous baffles spaced approximately 5.25 inches apart, as well as full down collar for sealing in heat around your head and neck.

What really sets this sleeping bag apart is its 16 ounces of down fill, five-inch loft for superior insulation and thermal efficiency, as well as an impressively low weight between 1.75 and 1.94 pounds depending on the bag size. Best of all, this bag can withstand temperatures as low as 20º F.

Whether your summer bike trip is taking you through different climates or you need a reliable sleep system for mid to high elevations, you can get more trail time and stretch your seasons while sleeping in comfort. You will not be disappointed with the UltraLite.

Chinook Polar Ice Mummy Down -22-Degree

The Chinook Polar Ice Mummy Sleeping Bag is a more affordable alternative to the SummerLite and would make an excellent investment for naturally warm sleepers that like to backpack in the colder months. The temperature rating of -22º F is credited to its 42 ounces of French Pyrenean grey goose down with 600+ fill power.

The outer shell is comprised of rip-stop nylon and features a baffled, horizontal channel design. As with any of the sleeping bags in our review, size-conscious backpackers will appreciate the included four-way compression stuff sack. However, added features comes at a price. The Polar Ice weighs in at a whopping 3.5 pounds, which is entirely too much for thru-hikers or ultralight hikers that cannot afford to sacrifice base weight for added insulation.

Conserving and eventually replacing all of the energy you burn while hiking is essential to maintaining health. By reducing pack weight while maintaining your body’s requirements for heat, you will have greater outdoor experiences. The Polar Ice is an excellent choice for mid-elevation treks or snow skiing trips, but we wouldn’t recommend testing beyond the specified temperature rating due to a lower fill power than the SummerLite.

SummerLite Overview

Deciding which sleeping bag is best for your travels and a good night’s sleep may have seemed daunting at first, but we hope that our thorough review of the Western Mountaineering SummerLite sleep system provides you with enough information to decide whether this product is ideal for your expectations and the environments you plan to explore.

Some of the most prominent features for you to consider before making your final decision should include temperature rating, down insulation and fill power, space, and packing convenience. The SummerLite is a reliable choice for hikers of small to medium stature who prefer sleeping on their sides or in contorted positions because of its slim mummy design.


  • Three sizes to choose from: 5’6”, 6’0”, and 6’6”
  • Weighs between 1.2 and 1.5 pounds
  • 850+ down fill power and four inches of loft
  • Mummy cut optimizes thermal efficiency
  • Ethically sourced plumage from free-range geese


  • Costly initial investment
  • Lack of water resistance or a DWR finish
  • Not as lightweight as competing sleep systems
  • Added hood and full-length zipper don’t save weight
  • Slim mummy design isn’t spacious enough for large hikers

If you keep your expectations realistic and choose a sleep system that is designed for the types of trips you traditionally take or plan to take, we are certain that you will make the smartest decision for comfortable sleep on your outdoor adventures. Another helpful way you can cut down on weight for your upcoming trek is by choosing a bag with a temperature rating no warmer than you realistically need.

To make your search even easier, we’ve provided similar sleeping bag models by competing brands and even the same manufacturer. We think that you’ll find the SummerLite to offer the best combination of features, and most mountaineers agree that they are the best in the business.

Western Mountaineering SummerLite Sleeping Bag
  • Packaging and Packability
  • Design and Durability
  • Size and Shape
  • Material
  • Insulation
  • Temperature Rating
  • Water Resistance
  • Unique Features
  • Value Verdict


Western Mountaineering’s SummerLite sleeping bag is ideal for mountaineers, thru-hikers, and ultralight hikers looking for a slim, lightweight alternative to reduce their overall base weight when venturing into medium to high elevations. This sleep system is also a great investment for anyone wanting 850+ down fill power and a temperature rating of 32º F, which is well below its closest competitors and offers a great value considering the number of features it includes.

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4 thoughts on “Western Mountaineering SummerLite Sleeping Bag: Sleeping Right and Light on Summer Adventures”

  1. I would like to commend you for a concise and complete review. I love reading all your articles to be honest. Anyway, Western Mountaineering is really an awesome brand. I bought this sleeping bag around two years ago and it is amazing. It is light and compact, making it perfect for trips.

  2. I am glad you included Chinook Polar Ice Mummy Down. I have used the sleeping bag for a few treks in the Himalayas and it was perfect for me. It kept me warm and comfortable. In a lot of ways, it made my trips more enjoyable. It is exactly as advertised. Two thumbs up for me.


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