Best -40 Degree Sleeping Bag for Surviving Extreme Cold Weather

Camping during winter is a test of endurance and fortitude. Many individuals enjoy testing their limits in harsh conditions, and winter may be the most brutal condition there is. If you are one of those individuals, there are several things you need to prepare, including finding the right winter sleeping bag. You need the best -40 degree sleeping bag your money can buy!

Even outside of winter, a good sleeping bag is an essential part of anyone’s camping arsenal. It might be hot during the day, but the temperature can quickly drop once the sun goes down. A tent may work to keep insects at bay, but it is not good enough to keep you warm.

The ability of the sleeping bag to retain heat becomes even more crucial if you are camping in negative temperatures. This list will help you find the right winter sleeping bag for your camping needs.


  1. What is a winter sleeping bag?
  2. Synthetic insulation vs Goose down-filled.
  3. Best -40-degree sleeping bags:
  4. Camping mat.
  5. Conclusion.

What Is a Winter Sleeping Bag? 

Regular sleeping bags won’t be of much use to you in the winter. For temperatures below 32 degrees Fahrenheit, you’ll need a winter sleeping bag. These bags often have linings filled with insulating materials and features like draft tubes, collars, zipper guards, and shell fabrics.

Sleeping bags that manufacturers design specifically for the winter come in two variations. One is a bag that gets a rating of 0 degrees. That’s for use during camping in areas that experience mild winters. If you are going to spend the night somewhere colder, you need to get the other variant. This is the bag that gets a rating of -20 to -40 degrees. You’ll need this bag if you want to camp in a high-altitude area like mountainous terrain.

As many experienced campers will tell you, it is much better to bring a sleeping bag that is too warm rather than one that is too cold. Having a bag that is insufficiently insulated may force you to cut your camping trip short or send you to the hospital.

Synthetic Insulation vs Goose Down-Filled

Besides keeping you warm, a winter sleeping bag should also keep you comfortable when you lie down on the ground. The lining of the bag provides comfort. There are two types of bags worth discussing: synthetic and down-filled.

If you want absolute comfort, then you need to get a goose down-filled sleeping bag. It is unparalleled when it comes to warmth and softness. It is almost like you brought your bed to the woods. This material is not very heavy and can be rolled into a compact bundle so that you won’t have a problem carrying it to your campsite. The primary downside to this type of lining is that it loses its insulation ability once it’s wet. That is why most manufacturers have started to treat them with coating. This coating makes the material water-resistant so that you can use it with convenience.

On the other hand, synthetic insulation doesn’t require a lot of maintenance. You don’t have to worry about the sleeping bag getting wet because the material dries quickly. In terms of keeping you warm, it is very close to the level that goose down has to offer. The main difference is that it is not as compressible as the other variant, so it may require additional space.

Best -40-Degree Sleeping Bags

-40-degree sleeping bags aren’t as popular as the other winter sleeping bags, especially since they’re for use in extreme temperatures. Not a lot of people are willing to subject themselves to such harsh conditions. Therefore, our list of the best -40-degree sleeping bags is relatively short.

1. Marmot CWM Sleeping Bag

The Marmot company started in 1971 as a social club of people who love mountaineering. In 1974, its two founders began making their sleeping bags and parkas during college. From that small venture, Marmot Mountain Works emerged. Gradually, the company expanded to what it is today; a top manufacturer of everything you need to fulfill your camping desires.

Features of the Marmot CWM

Marmot CWM Sleeping Bag

Marmot designed this particular sleeping bag to help you survive in the death zone. It is a -40 degree bag made to get you through the coldest weather conditions on the planet. What makes this sleeping bag toasty and comfortable is the 800-fill goose down. Now, we know that down can be tricky to manage since it shouldn’t get wet. Unfortunately, when the snow melts, it turns to water. That is why Marmot used a waterproof yet breathable material called the Pertex Shield 2L. This lamination prevents moisture and condensation from ruining your sleeping experience inside the tent. It also protects the goose down from getting damp, allowing it to retain its insulation capabilities.

As an added protection against moisture, the manufacturer constructed the outer part of the bag using 30D nylon ripstop. The manufacturer used Pertex Microlight for the inside of the sleeping bag. This material has a soft feel but extreme durability to avoid any rips that would leak out the feathers. This bag should last you for several years without ripping.

Marmot chose the mummy shape of the bag to keep the warm air closer to your body. It even has a hood with drawstrings, allowing you to adjust it according to your preference. The bag unzips on each side for easy access. It also has zipper guards so that it won’t get snagged onto the fabric.

When it’s time to break camp, the Marmot CWM Sleeping Bag can easily be rolled and packed inside its stuff sack. The sleeping bag only weighs 2268 grams, so carrying it shouldn’t be a problem. You can bring it in your pack, and you won’t even realize it’s there.


  • Made from waterproof, breathable material called Pertex Shield 2L
  • Prevents moisture condensation
  • Outer material uses 30D nylon ripstop fabric
  • Customizable with adjustable drawstrings
  • Lightweight design


  • Zipper is faulty

2. Forceatt Mummy Sleeping Bag

For tall adults, one of the best options out there is the Forceatt mummy-shaped sleeping bag. It is over 75 inches long and has a shoulder circumference of one hundred sixty centimeters. That’s ideal for adults because you’ll fit snugly in the bag at night. Having too much space between your body and the bag will affect its insulation and not keep you as warm as it should.

Features of the Forceatt Mummy Sleeping Bag

Forceatt Mummy Sleeping Bag

This bag comes with a drawstring hood and an inner neck surrounding it. These features keep the cold wind out and the warm air in. Combined with the 400g/m² filling material, the bag should keep you feeling warm even when the temperature drops below 32 degrees.

A 220 hydrophobic polyester fabric makes up the outer part of the sleeping bag, allowing the bag to be waterproof. The manufacturer designed this material to allow water molecules from inside the bag to escape. This mechanism will keep you from sweating in your sleep.

Do your feet get cold quickly? The Forceatt sleeping bag features an innovative design for its foot box. It is arched and has extra heat insulation to keep your feet feeling toasty despite the extreme conditions outside.

The zippers also come with anti-snag features. The internal and external anti-bite technology keeps the zipper from getting stuck in the bag’s lining. This will allow you to zip up quickly, preventing the cold from getting into the bag as you are settling down for the night.

If you are sleeping on the ground and worry about your bag not being tough enough, the Forceatt sleeping bag has got you! The outer fabric of this bag uses the latest lattice weaving technology. This gives it additional durability to resist tearing and also prevents the bag from becoming deformed.

Once the camping trip is over, you can pop the sleeping bag in the washing machine and give it a good wash. You don’t even have to spend money on cleaning your bag for the next trip.


  • 400g/m2 filling to keep you warm
  • Outer part is made of waterproof 220 hydrophobic polyester fabric
  • Separate insulated foot box to keep your feet warm
  • Anti-snap zipper
  • Machine washable


  • Zipper is buggy

3. Browning Camping McKinley Sleeping Bag

Browning Camping McKinley Sleeping Bag

ALPS Mountaineering was established in 1993 and grew to be one of the most premium manufacturing companies for high-quality outdoor products. One of their bestsellers is the heavy-duty, sub-zero sleeping bag known as the Browning Camping McKinley.

It offers the comforts of a rectangular pack but the warmth of a mummy bag. It is 36 inches wide and 90 inches long, which means there’s enough wiggle room for an adult to get a good night’s rest during an adventure.

The outer layer is made from a 210T Nylon Diamond Ripstop. This material is highly durable and prevents ripping effectively. It is water-resistant but not waterproof, so you’ll need to be a little more careful in deciding where you place your sleeping bag.

The inside of this bag has a lining of brushed polyester. This material is soft and comfortable and almost like sleeping on a smooth blanket.

The Browning Camping McKinley design features a double-layer offset construction. This design eliminates any cold spots on the bag. It also comes with zipper baffles and a contoured hood to maximize heat retention.

Plus, the bag uses 7-denier Tec Loft Silver insulation. That refers to the micro-denier fibers with multi-hole features. Each fiber has a siliconized finish to ensure maximum insulation and compactness. This technology allows the bag to retain any heat coming off the camper’s body effectively.

When it is time to move, you can quickly pack this sleeping bag into its compression stuff sack. The bag weighs slightly under 13 lbs, so it is not as light as the other brands. Luckily, It comes with a roll-up strap to make carrying the sleeping bag more convenient.


  • Comfortable mummy bag design
  • Outer layer is made of waterproof 210T nylon diamond ripstop
  • Double-layer offset construction for better protection against cold
  • Easy to carry with the roll-up strap


  • A bit heavier than other sleeping bags

Do You Need a Camping Mat?

After choosing the perfect extreme temperature sleeping bag, you might wonder if you still need a camping mat. The short answer is yes. Even the best bag won’t protect you from the cold that will seep into your body from the frozen ground.

Placing the down-filled sleeping bag directly on the ground will compress the filling. Once it has turned flat, it will no longer have the same thermal capacities. The camping mat is there to prevent this from happening. Plus, it will keep your sleeping bag away from the melting snow and keep it dry.


When you want to compete against nature, winter camping is a great adventure to take on. But before you set out, make sure you have all your essentials with you. Winter camping certainly isn’t something you can try and get away from unscathed if you’re not well prepared. Part of that is to have an excellent winter sleeping bag. Sleeping on the frozen ground is no joke. The best practice is to have a bag that prevents the cold from getting in and something that keeps your body heat trapped inside.

The best -40-degree sleeping bags listed above are all tested for the harshest conditions. They’re also rip-proof and water-resistant, so they should keep you warm during frigid nights when you need a good night’s rest. A quality sleeping bag is definitely top priority for your tactical bug out bag list.

Share on facebook
Share on twitter
Share on pinterest
Share on email

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top