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!

Best -40 Degree Sleeping Bag

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.

What Is a Winter Sleeping Bag? 

What Is a Winter Sleeping Bag? 
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. Ha

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. High Peak Outdoors Cascade

Special Features

  • Thermal Collar.
  •  barrel lock.
  • Hood and Drawstring closure.
  • 2 Bags can be zipped together.

To passionate trekkers, the High Peak Outdoors Cascade -40-Degree Sleeping Bag, is one of the most essential components that can help them to get a sound sleep in the lap of snow. This is a mummy-shaped cold weather 4-season sleeping bag. Compared to the others, this product has a cheaper price tag, but the quality is not compromised here.

The shape and size of this bag are perfect for adults. It measures 86 inches long, and 34 inches wide, and it is 22 inches wide in the foot area. The size of this sleeping bag is ‎X-Large. Anyone can easily fit himself within it and find some comfort in that frizzing cold. 

This product comes with a compression stuff sack. It helps the users to carry it easily from place to place. It weighs only 8 pounds. Two ways zippers are present in it and these are smooth and easy to use. If you want, you can zip two bags together side by side.

 The thermal collar of this bag is so effective that you can find great comfort on the most frigid nights. The soft material that is used here, ensures great comfort. Invista Tactel Quallo is used here for insulation purposes and Nylon Taffeta is used in the shell of this bag. The quality of the barrel lock is also superb. The hood and drawstring closures are also easy to use. 

When you are within this Gray and Red colored sleeping bag, then it is very difficult for you to realize the bone-freezing temperature of the outside. This is a great product that can offer you some comfort and warmth in freezing weather.


This sleeping bag is available at a pocket friendly price tag.
✅ Good quality materials are used here, so it is very durable and effective.
✅ Being comparatively light, it is easily carriable.


It is not completely waterproof; it is water repellent.


This is a great value for money product. It is very effective and its quality is superb. This sleeping bag is a very fruitful product for the adult mountaineers, who need to spend nights near the glaciers.

2. Western Mountaineering Bison GWS

Special Features

  • Huge V-Block Side Baffles.
  • Insulated External Hood Ruff.
  • Double Interlocking Draft Tubes.
  • Full Down Collar.
  • Gore Windstopper fabric.

The Western Mountaineering Bison GWS -40 Degree Sleeping Bag is the perfect example of the combination of comfort, quality, and effectiveness. It is so effective that you can’t sense the frigid temperatures out there when you are with this semi-rectangular-shaped sleeping bag. 

This -40 degree sleeping bag weighs around 4 lb 10 oz. It has a length of 6 feet, so it is ideal for any adult. It has a loft of 10.5 inches. The inside girth of this bag around the shoulder is 64 inches. Around the hip, it is 55 inches and 39inches around the feet. The stuff sack measures 11 x 22 inches. So you will not have any hassle while carrying it. The red colored sleeping bag comes with good quality zippers. 

The sleeping bag is made with gore wind stopper fabric. So, it will help you to keep the inside of your sleeping bag dry by not allowing water to pass through. The sleeping bag also comes with a heat trapping loft, which will maintain the warmth even if the wind is extreme and freezing cold. 

The massive insulated external hood offers great comfort and Gore Windstopper fabric is also used here. There is a large integral hood ruff that protects your face. This innovative, great quality sleeping bag is always there to give you some comfort and warmth in the freezing nights of the mountains.


The sleeping bag is very comfortable.
✅ There is a very effective heat locking mechanism that keeps the inner temperature very warm.
✅ This light but the impervious bag can resist up to -40 °C or -40 °F.


This is a costly sleeping bag.


This may be a costly sleeping bag. But, you can find great warmth, comfort, and portability in it. For professional mountaineers, this is a great choice. 


Special Features

  • Down-Filled Draft Tube.
  • Hidden Draft Tube Pocket.
  • Ground-Level Side Seams.
  • Cross-baffle construction.
  • a waterproof Pertex shell.

The MARMOT CWM Long is a Mummy-shaped sleeping bag. It is always ready to protect you from the freezing weather. It uses an 800-fill-power goose down that protects you down to -40°F. A waterproof Pertex shell is used in this product that keeps you dry in that immense freezing temperature. The temperature rating of this Redstone colored bag is -40 degrees. 

The manufacturer has used Pertex Shield 30-denier 2-layer ripstop nylon on the shell of this bag. The zippers that are present in this bag, are placed on the left side of the bag. The lining of this bag is of Pertex Microlight 30-denier ripstop nylon. 

The Stuff Sack of this product measures 9.5 x 19 inches. To prevent the bag from shifting and to eliminate cold spots, the manufacturer has used cross-baffle construction here. To increase warmth they also used an 11-baffle, wraparound footbox. It also offers ample foot space. Nautilus 6-baffle hood keeps the bag in its place.

A down-filled draft tube is present there. The zippers are backed by it. Feely drawcords make it easy to adjust in the dark. To keep the warm air inside, the liner is placed above your shoulders. Heat is distributed inside the bag effectively with great baffling. The baffles make this sleeping bag more durable. The quality of the zippers is great and these prevent snagging. 


This sleeping bag is quite spacious.
✅ There are six baffles to provide heat in the hood chamber.
✅ This sleeping bag is very effective and can keep your body warm.


❌ It is very difficult to pack it into a stuff sack.
❌ It is not good to be used in a moderate cold.


This is a good quality waterproof sleeping bag. It is one of the best options for professional mountaineers.

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.

Frequently Asked Questions (FAQs)

What temperature is a 20-degree sleeping bag good for?

A sleeping bag’s temperature rating indicates the lowest temperature at which it can maintain sufficient warmth. A sleeping bag rated at 20 degrees will provide adequate heat when the outside temperature is at least 20°F or slightly above. For summer camping a 20-degree sleeping bag is a good option.

What is the best degree for a sleeping bag?

In general, a 20° bag can be used throughout the year and you will not feel much discomfort. But, practically you need to choose this temperature rating according to the weather of your destination. For example, if you are near a glacier, then only a sleeping bag with a -40 degree rating can give you comfort. Similarly, it will be useless in a moderate cold. So the perfect temperature rating of a sleeping bag varies from place to place.

How good is a 0-degree sleeping bag?

A sleeping bag that has zero degree temperature ratings means that that bag is suitable when the outside temperature is 0 degrees Fahrenheit. For trekking in mountains, a 0-degree sleeping bag is a good option. But you can’t use it on your summer trips.


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.

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