How To Stay Warm In Your Tent: Science + Tips

It might seem challenging to know how to stay warm camping, especially when you’re trying to stay warm in your tent! But you don’t have to suffer through cold nights for gorgeous days– even when you’re camping in winter, you can stay nice and warm in your tent. You just need to know a little bit about why you get cold in the first place!

See, tents aren’t built like houses or even cabins. When you’re staying in a cabin, there are lots of thick insulating materials and a foundation under the building that elevates it away from the cold ground. If you’re trying to figure out how to stay warm in a tent, it helps to know a little bit about why you get cold in the first place.

 

The Thermodynamics of Camping

To understand why these tips work for keeping warm in your tent, it makes the most sense to understand a little bit of the science behind how heat transfer works.

There are four basic principles you should understand when you’re trying to stay warm in a tent: convection, conduction, radiation, and evaporative cooling.

 

Convection

Convection is the transfer of heat from one place to another due to the movement of fluid or gas. This is why a breeze can cool you off, even when you’re not sweating… and why an icy winter wind can be deeply unpleasant. You will lose heat to convection when your body is exposed or improperly insulated.

 

Conduction

Conduction is the transfer of heat between two solid surfaces that are in direct contact with each other. You’ll lose heat to conduction if you don’t have insulation between you and the ground because when you’re camping, the ground is going to be cooler than your body temperature. Even in summer, the ground temperature where you’re camping might not be body temperature.

 

Radiation

Radiation is the loss of heat through the increased surface area. If you’ve ever wondered why elephants have big ears, it is because that increased surface area helps keep them cool through radiation. Conversely, animals that live in colder climates are more compact and have smaller appendages. (If you’ve studied biology, you might be familiar with this as Allen’s Rule.) The more surface area exposed to the air, the more heat you’ll lose through radiation. When you’re camping in cold weather, you need to think about heat loss through radiation primarily when you’re choosing clothing and sleeping bags.

 

Evaporation

Evaporative cooling is heat lost through the process of evaporation. This is why we sweat when it’s hot. It’s also why wet clothes work against you when you’re trying to stay warm.

 

Heat Rises

A fifth principle affects you when you’re choosing a camping spot. Hot air rises and cold air sinks. This means that if you’re camping in a valley, you’re going to be camping in colder air than if you were camping up on a ridge. However, peaks and the tops of ridges are exposed to weather conditions like higher winds and lightning strikes, so if it’s cold or rainy out, your best bet is to camp at a mid-level elevation. Find your “Goldilocks” spot– not too hot and not too cold, not too high and not too low.

In addition to finding a camping spot, you can also think about the heat within your tent that will rise to the top of the tent and get stuck there. Tents with a shorter height may be less comfortable to stand in, but your body heat will have less room to travel, and having a smaller tent can make it so body heat keeps the tent warmer than it would with a larger tent.

With these principles in mind, let’s look at some tips for how to stay warm in a tent. We’ll share some tips to think about when you’re choosing your gear, when you’re packing your clothes, and when you’re actually out camping.

 

Gear Tips

Ever hear the saying “an ounce of prevention is worth a pound of cure”? When you set yourself up for success by choosing and bringing good gear, you’re less likely to find yourself in an uncomfortable or even dangerous situation.

 

Use A Sleeping Pad

When you’re the warmest thing in the tent, you’re not just going to lose heat to the air; you’re going to lose heat to the ground as well. Don’t put your sleeping bag directly on the ground– use a sleeping pad. Even a light, inexpensive sleeping pad is better than nothing, because foam is a good insulator. Don’t use a tall air mattress– the air inside will be cold and unless you put a pad on top of the air mattress, it will cool you down. However, thinner inflatable pads can work really well in cool weather– it all depends on how they’re made.

 

Pay Attention To R Values

When you’re choosing a sleeping pad, look for one with a high R-value. A foam sleeping pad’s R-value ranks its ability to resist heat transfer. The higher the R-value, the better the pad is at insulating. Pads are scored from 0.5 to 5.5, with 0.5 being the least insulating and 5.5 being the most insulating.

 

Get A Sleeping Bag Liner

A fleece sleeping bag liner can add a little extra oomph to your sleeping bag’s ability to insulate. Fleece is a great material for insulation, and it’s comfortable to sleep in. Sleeping bag liners are often inexpensive when compared to investing in another sleeping bag, but can add a ton of warmth to your existing setup.

 

Think About Tent Material

Tents can be made out of lots of different materials, some of which are better at insulating than others. When you’re looking at a tent you already have, make sure that its waterproof coating is up to date and that there aren’t any unwanted holes. If you’re going to buy a tent for cold weather camping, look for one that’s rated as a 4-season tent or has been designed with winter camping in mind.

 

Consider A Smaller Tent

There are lots of types of tents out there, but when you’re camping in cold weather, a small tent means that there’s less air to heat up. Less headroom means that your body heat is escaping into a smaller airspace and convection has less of an effect.

 

Bring A Mylar Blanket

Emergency mylar blankets are great at reflecting heat and keeping you warm. They’re uncomfortable to sleep under, yes, but that’s not what you’re bringing one for. Instead, take the mylar blanket and tape it to the top of your tent, shiny side facing you. You can also lay one on your mattress or sleeping pad, shiny side up, to help preserve heat.

 

Keep Your Sleeping Bag Dry

After a good night’s sleep in your sleeping bag, don’t forget to unroll it to dry any moisture that has collected in it. If it’s damp at all, it will make you feel colder at night. To dry the sleeping bag, unzip it as much as possible or turn it inside out and lay it out. Make sure that the whole interior surface is, and it’s even better if you can hang it somewhere. But if there’s any rain or snow in the forecast, don’t hang it up– leave it in the tent. Some dampness from sweat will always be better than allowing the bag to get soaked.

 

Don’t Forget Your Hot Water Bottle

Hot water bottles are great for keeping warm in your tent at night. You can use a rubber or silicone soft bottle, or you can just use an insulated water bottle that can handle hot liquids. As long as you have a pot, a camping stove, or some way to get that pot hot in the campfire, you can boil some water, pour it into a sturdy, leak-proof water bottle, and stick the bottle in the bottom of your sleeping bag. Your feet will absorb the heat from it, and the rest of your body will warm up.

You can also use an uninsulated bottle. Don’t fill this with boiling water, as it can ruin the bottle– but if you fill this kind of bottle with hot water, you can keep it near your feet, neck, knees, inner thighs, or any other major node of your circulatory system.

 

Clothing Tips

The clothing you choose can make or break a camping trip. Here are some tips for choosing clothes that will keep you comfortable and warm while camping.

 

Layer Up

Choosing an appropriate base layer can make all the difference in the world when it comes to staying warm in your tent. A base layer that can wick away moisture while effectively keeping you warm is worth its weight in gold. While there are lots of great base layers out there, for really cold weather Merino wool might be your best option. It’s an incredible insulator that can keep you warm even if it gets wet.

 

Don’t Sleep In Your Day Clothes

Sleeping in your day clothes means that if there’s any moisture from sweat, it will stay with you in your sleeping bag. It will feel gross and clammy, and more importantly, it will put you at risk of temperature loss from evaporative cooling. You should bring something to sleep in and only use it for sleep– a set of thermal long underwear is perfect for this.

 

Know Your Options

You need to think about the fabric your clothes are made out of and what that fabric can do. A long-sleeved cotton shirt and a long-sleeved wool shirt perform very differently! Before any hiking trip in any weather, it’s a good idea to review the different types of fabric and compare them to each other. This will help you know what exactly you’re looking for. We have guides to several types of fabric, including:

•  Wool Vs. Cotton
• Polyester Vs. Wool and Merino Wool
• Fleece Vs. Wool
• Fleece Vs. Polyester
• All Types of Wool

Wool, fleece, and synthetic blends are most common for cold weather uses, where cotton is almost never recommended for cold weather.

 

Stay Dry

You might think that wrapping up with lots of thick layers and blankets will keep you warm, but if you get too warm, you’ll start sweating. And that will cool you off, which you don’t want. You want to maintain a happy medium, so use thinner layers that you can remove once you start feeling hot. It’s more dangerous to drench your clothes and sleeping bag with sweat.

 

Use Tent Socks

Your feet are very sensitive to temperature. They’re highly vascularized, which means that a lot of blood flows to and through them, and that means that they’re very susceptible to the cold… and you can lose a lot of heat through them if you’re not careful. Have a pair of thick, woolen socks that you only wear in the tent at night. This will ensure that they’re dry and will help you stay warm.

 

The Myth Of Head Heat Loss

You might have heard that you can lose up to 50% of your body heat through your head, but that’s actually false. In reality, you only lose between 7% and 10% of your heat through your head. So you don’t need to wear layers and layers of material on your head at night– especially because it may make you sweat more! A comfy cap is better than a stifling balaclava. That being said, the more you cover your head, the more you will be warm. Sleeping with a beanie next to you is a good way to easily regulate temperature quickly if needed. Putting your head inside your sleeping bag will warm you up, but you’ll quickly feel the moisture of your breath building up in your bag. If you need to mummy up for warmth, find a way to let your breath leave your sleeping bag.

 

Action Tips

These tips are things you can do when you’re out on the trail or in the woods. You can’t just rely on your gear to keep you warm– you have to take the proper steps to give yourself the best possible chances of staying warm and dry in your tent.

 

Eat Up!

If you think of the body as a furnace that produces heat, food is the fuel it uses. Try to eliminate any caloric deficit you may have. You should have a meal not long before you sleep, and that meal should be fueling your body where it is deficient. That likely means you’ll need a balanced meal of fat, protein, and carbs to set yourself up to be as fueled as possible. Your body may not be producing as much heat if you are in a caloric deficit.

 

NO Alcohol!

Alcohol is the worst thing you can drink when you’re cold. It makes you think that you’re warm but actually lowers your core temperature and inhibits all thermoregulatory functions. Don’t risk it.

 

Hydrate During The Day

Once you’re winding down for the night, avoid drinking too much. The reason for this is that you don’t want to have to leave the tent to pee. You’ll let cold air in. If you do have to use the bathroom at night, some campers like to have a designated bottle for that use so that the tent door doesn’t have to open. That being said, make sure you are hydrated. Being hydrated is important. Drinking warm liquids can help as well.

 

Use A Tent Safe Heater…

But ONLY when you’re awake! It’s totally fine to preheat the tent and have the heater on while you’re getting ready for bed, but they should be turned off when you’re actually going to sleep. Make sure it is a tent safe heater and doesn’t release gases that could kill you or make you sick.

 

Use Your Mummy Bag Correctly

If your sleeping bag is a “mummy” style bag that has a hood, use it! The more of your body you cover, the less heat you’ll lose to radiation. A mummy bag will let your nose and mouth stick out but cover the rest of you.

 

Go To Bed Warm

Some people recommend a little exercise before crawling into your sleeping bag, but don’t go too far with this. If you do five hundred jumping jacks, you will find yourself warm… and sweaty. And that means that you’re going to be cold once that sweat starts to evaporate! A little light exercise is fine, but don’t overdo it. You want to go to bed warm and dry, not hot and wet!

 

Set Up Proper Ventilation

This might sound counterintuitive, but if you want to stay warm, you need to keep the tent ventilated at night. The heat from inside your tent can lead to condensation building up on the walls, which makes everything inside the tent feel damp. This will make you colder. Keeping the tent ventilated and dry will make you feel warmer. You don’t have to let in a strong wind, but make sure that there’s enough ventilation that condensation evaporates.

 

Snuggle Up

Cold weather isn’t the time to be super invested in personal space. You don’t have to share a sleeping bag, but sleeping close to another person will help conserve body heat between the two of you. If you do share a sleeping bag, remember that you don’t want to sweat! You may need to use fewer top layers if you’re planning on sharing a sleeping bag.

 

Add A Dog

If you’ve ever heard the phrase (or heard of the band) “three dog night,” you might know what we’re referring to. A three-dog night is a night that’s so cold, you need three dogs in the bed with you to stay warm. Dogs make great cold-weather sleeping companions; not only are they naturally snuggly, but their body temperature is naturally higher than ours is.

 

Use Hot Rocks

Ask any lizard: a nice hot rock, warmed by the heat of the sun (or the campfire) is a great way to stay warm. When you’re building your campfire, collect a few small to medium-sized rocks and place them near the edge of the fire. Let them soak up the heat for an hour or so, then pull them away to cool. You don’t want them to be blazing hot– you want them to be hot, but handleable.

Once you have some nice hot rocks, you can wrap them in a towel and pack them into your sleeping bag. Hold them near your core, your feet, your inner thighs, or your neck for a DIY, reusable, safe, and eco-friendly sleeping bag heater. Another option that works great if you have larger stones is to set them in the middle of your tent and let them radiate warmth. This works especially well if you’ve put a mylar blanket on the ceiling of your tent.

 

Listen To Your Body

Shivering is a warning sign. When your body gets cold, you start shivering to generate the heat that you’re losing. By the time you start shivering, you’ve already begun to lose some of your core temperatures, so as soon as you notice that you or a body is shivering, it’s time to get somewhere warm. Get closer to the fire, add another layer, or get to some kind of shelter. Also, be aware that the body stops shivering when the muscle contractions are no longer effective in producing heat. When somebody stops shivering but hasn’t gotten out of the cold, that doesn’t mean they’re warm again. It might actually mean that hypothermia has begun to set in.

 

The Top Tip: Stay Dry

This might be the single most important tip on our list. Even in the summer, getting wet while hiking or camping in wet conditions can lead to hypothermia. Hiking and camping in cold weather can be beautiful and amazing, but no camping experience is worth risking your life. To make your experience as safe as possible, stay dry when the weather is cool. Use moisture-wicking base layers to ensure that sweat doesn’t stay on your body, and bring enough extra clothes that you have something to change into if you do get soaked. Pay attention to the weather, and know that there’s no shame in turning back if you have to!