The Science of Hammock Camping in Cold Weather: How to Stay Warm and Comfy

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Hammock Camping? In the cold? Is that even possible?! Turns out, yeah. Yeah it is. We’ve done it. So have plenty of other intrepid outdoorists who don’t let a little cold stop them from sleeping outside. But here’s the thing: hammock camping in cold weather is a lot different than hammock camping when it’s hot. It’s also different than tent camping in cold weather. We’re gonna break down exactly why and how that’s the case, plus share a few tips for comfortable winter hammock camping so you can sleep comfortably any time of year.

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Check out our review of a suitable winter camping hammock, the Haven Safari.

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Hammock Camping in Cold Weather: Why is it Different?

So why does sleeping in a hammock result in such a different experience when it’s cold outside? Well, Science. That’s why. So we’re gonna dive into not just how tent vs hammock camping in the cold is different, but why, scientifically speaking, why it matters, and what the heck to do about it. Including how to effectively combat the cold with the right gear so you can sleep warm and happy year-round.

Why do such a deep dive? ‘Cause hammock camping is super comfy. And if you prefer sleeping in a hammock to sleeping on the ground in the summer, then you should know that you can, indeed, sleep suspended in the air when the mercury plummets, too. You just have to know what the unique challenges are, why extra precautions and gear are necessary, and what gear you need so you go out there prepared (to not freeze to death).

So let’s talk about all the different ways your body can and will lose heat and make you feel cold. Whether or not you’re sleeping outside. 

Types of Heat Loss

There are four main ways your body loses heat: Evaporation, radiation, conduction, and convection. (Plus respiration, but that’s a comparatively minor one.)

• Evaporation is when you are damp, say from sweat, a spilled water bottle or a slip in a creek. As that moisture evaporates, it takes some of your body heat with it. That’s one reason it’s so important to dress in layers during outdoor adventure (and while sleeping) to avoid soaking clothing with sweat when you’re exercising in the winter: Damp clothing–even from sweat–makes you feel colder.
• Radiation is when heat simply leaves the body due to exposed skin. The majority–65%–of your body heat is lost to radiation. That’s why your mother is always yelling at you to wear a hat and zip up your coat: the best defense against this type of heat loss is to bundle up and trap body heat in insulating layers.
• Conductive heat loss is when your body comes in contact with something cold, like frozen ground, snow, or a cold metal bench. It effectively sucks away your body heat in some sick natural obsession physics has with reaching temperature equilibrium.
• Convective heat loss is similar, but involves air instead of a solid surface. It’s the second largest way your body loses heat. It happens when a cold breeze blows and lowers the temperature of whatever body part it contacts that’s not protected from wind-proof materials. This type is why you might see an actual temperature of 30º but with a windchill that makes it feel like 20º. The movement of air can make you feel significantly colder.

There’s also respiration heat loss, essentially what you lose to breathing, but that’s usually minimal.

What does all this have to do with hammock camping? And how do you use this info to stay warm outside?

How to Stay Warm When Hammock Camping

Here’s how to use what we know about science to stay warm when hammock camping in cold weather.

Evaporation

Let’s start with evaporation. Because it’s an easy one. Wanna stay warm? Don’t be wet. Don’t go to bed wet. Put on warm, dry layers right before you get into your bag–including socks–so there’s no chance anything is even damp from sweat. Keep your gear dry. Don’t spill your hot water bottle inside your sleeping bag. And don’t go to bed in so many layers you’re likely to wake up sweating. ‘Cause then you’ll end up wet.

Radiation

Next up: radiation heat loss. To prevent this and stay warmer, cover your dang body with insulating layers, as in, a warm base layer, maybe a cozy layer like a Cotopaxi Teca fleece, but don’t go crazy, because your final layer should be a warm sleeping bag. And in order to make that sleeping bag nice and cozy, you’ll need to fill the space with your body heat, which won’t happen if you’re wearing seven layers inside the bag.

Let the bag do its thing, OK? But that does mean you’ll probably need a bag with a temperature rating at least 10 degrees below the lows you’re expecting because ratings are weird and usually misleading. We wrote an article explaining sleeping bag temperature ratings HERE.

You can use a quilt instead of a bag, but since hammocks are draftier than tents, a full mummy bag with a hood will keep you warmer, especially if you tend to sleep cold.

Conductive

Then there’s conductive heat loss. Which, since you’re suspended above the cold ground and not touching it like you would be in a tent, is not really an issue when winter hammock camping.

Convective

But it’s related to convective heat loss, which can be a HUGE problem in a hammock. And maybe the most important to combat. That’s because air can swirl all around you: top, bottom, and sides, including right under your butt, which will make you feel way colder than you would in a tent with an insulated sleeping pad.

Fortunately, there are several ways to combat convective heat loss, starting with an underquilt. No, seriously. Without one, body heat will be sucked right out of you from beneath. Why? Wouldn’t a sleeping bag prevent that? Well, no, because any bag insulation that you’re laying on top of gets compressed, so it doesn’t actually offer any insulating properties anymore. 

An underquilt, on the other hand, hangs below your hammock, so it’s not crushed by your body weight and can more effectively block cold air from hitting your butt and causing CBS (Cold Butt Syndrome). It effectively keeps out the wind plus traps a little body heat. And it is best to use a dedicated underquilt because they tend to be longer and stretch all the way from one end of your hammock to the other better than, say, a top quilt or a Rumpl blanket or something.

In addition to an underquilt, you probably also want to pack an insulated sleeping pad, which does wonders for further protecting you from that convective heat loss. In not-so-cold temps, a closed-cell-foam pad may be sufficient. But frankly, they’re always rectangular so don’t fit in a hammock very well. I prefer an insulated inflatable mummy-shaped pad with an R-value of at least 5. The higher the number, the warmer it is. I prefer my Nemo Tensor Extreme pad with an R-value of 8.5 on winter camping trips (read about what R-value is HERE).

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Other Tips: How to Make Hammock Camping More Comfortable

Want to know what to bring hammock camping (in the winter or otherwise)? Or extra tips for sleeping warm in a hammock? We got you.

• Two-person hammock: While you may be tempted to pack a one-person hammock because it’s smaller and lighter, a two-person hammock, especially if you’re tall or have a larger frame, will be more comfortable. It will make it easier to stretch out diagonally so you can lay flat (we created a whole video on how to comfortably sleep in a hammock, by the way).
• Tarp or fly: To further protect from convective heat loss, hang a tarp or fly close and tight against your hammock. This helps trap a bit of body heat that might escape your bag, which it will do better the less space there is between it and your body because it means there’s less space to fill. But it mostly protect you from wind from the top and sides, especially when the edges of the fly descend lower to the ground.
• Neck gaiter: If it’s really cold and you’re worried about respiration heat loss, bring a lightweight neck gaiter that you can pull over your nose and mouth. I like this balaclava-style option from Buff with small slits to make breathing easier while still offering some insulation.
• Nalgene: Fill a water bottle with hot water and toss it into your bag at bedtime. Just make sure the lid is on super tight so it doesn’t leak.
• Hand and foot warmers: When tucked into chest pockets or between your thighs, they’ll keep you warmer for hours. I like the ones from Ignik.
• Fill your bag: Stuff any extra clothes in your bag with you. That will help fill up empty space and insulate you even more, plus your clothes won’t be freezing cold when you put them on in the morning.
• Pack ultralight camp slippers: Camp slippers are packable, much warmer than thick socks, and are oh so comfy.
• Hammock stand: Hammock camping without trees? Pack a stand so you never have to worry about where you’re going to hang your hammock. We love our Kammok Swiftlet.

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Bottom Line: Hammock Camping in Cold Weather

See? Look how easy hammock camping in cold weather is once you understand what type of heat loss you’re battling. If you’re like me, once the science is explained, it makes a heckuva lot more sense how to prepare and combat the cold when winter hammock camping.

What are our favorite hammock camping sets? The Kammok Mantis UL and ENO SubLink Ultralight Hammock System (pictured in this post), both of which come with all the basics (though underquilts, pads and bags are sold separately).