Q&A: How to stay warm when camping 

I recently found myself on an overnight camping trip with a group, many of whom hadn’t done a lot of camping before. Despite it being a warm day, the temperature dropped significantly at night and some people were extremely cold and uncomfortable. In the morning, amidst cheerfully-shared stories about lying awake shivering all night, a few people expressed surprise that their seemingly warm sleeping bag wasn’t up to the job on what was, after all, just a chilly autumn night in Southern England.

There were lots of reasons, and in some cases people just had rubbish or inadequate sleeping bags, but if you’ve ever found yourself in a similar position of being far colder at night than you expected to be, or you’re thinking of doing some camping over the winter – here are answers to some of the questions you may be asking yourself.

How do you make sure your sleeping bag keeps you warm?

Make sure it fits

This is most relevant to the taller amongst you, as having a sleeping bag that is too large is generally not an issue. Having a sleeping bag that is too small, however, is. If bits of you (most likely your feet) are pressed against the sleeping bag, stretching it out, then you will be compressing the filling and essentially exposing that part of your body to the cold air outside.

As I’ll keep reiterating throughout this post, sleeping bags work by trapping air – if air isn’t trapped by the filling then they’re no more use than a very thin blanket.

Use a sleeping bag liner for extra warmth

Liners aren’t a must-have, and their purpose is at least partly to make cleaning the sleeping bag easier. But, if you suspect you are going to be using your bag at something approaching its temperature limit, you could consider a lightweight fleece liner which, for a very small amount of added weight and bulk, will give you a little extra warmth.

Check the comfort temperature, not the minimum temperature 

Make sure you are aware of what your bags temperature rating and what that really means. Some sleeping bags will publicise minimum temperature ratings that are, essentially, that temperature at which someone in the bag will not get hypothermia. That is clearly not a suitable temperature to use it for a comfortable night’s sleep.

Fortunately there is a European standard for temperature ratings, and if your bag advertises these, they are a better guide so long as you understand what they mean. They will have three temperatures – the first is the temperature where an average woman lying flat will not wake up during the night, the second is where an average man lying curled up will not wake up, and the last is the temperature where a person will not get hypothermic. Since being warm enough to not wake up is probably your main goal, the first two ratings are a far more useful guide.

What should you wear to stay warm in your tent?

Sleep in a hat 

Even in a sleeping bag with a hood, drawcords pulled tight, your head is often the bit that most sticks out, and can be a serious source of heat loss. On any night that is even slightly cold, I’d strongly suggest wearing a hat to sleep, it makes an enormous difference to how warm and comfortable you will be, and you’ll value it even more in the morning as you start to get out of your bag and sort your kit out.

Be prepared to wear clothes

The European standard assumes a layer of thermal underwear as a minimum and many sleeping bags, especially serious expedition ones, are oversized specifically to allow clothes to be worn. That’s partly because it’s simply not realistic to expect people in extremely cold conditions to strip most of their clothes off for even the short time it takes to get into a sleeping bag, and it’s partly because it just makes sense from a weight and efficiency point of view. When weight is a concern, it doesn’t make sense to be packing all of your insulating layers in your backpack at night, and climbing mostly naked into an extremely heavy and warm sleeping bag, when you could just take one that’s a bit lighter, and be prepared to wear your down jacket to sleep.

What other kit will keep you warm on a camping trip?

A decent sleeping mat makes all the difference

This is perhaps the most important and easily overlooked point. A sleeping mat is not really about comfort, it’s about warmth. If you’ve ever tried sleeping on bare ground, or even directly on a camp bed, you’ll know how quickly warmth is sapped out of the part of you in contact with the ground or the bed. The reason is two-fold: Firstly the ground actually conducts heat much better than air. Second and more importantly, lying on anything crushes the filling in the part of your sleeping bag between you and the ground, making even the thickest sleeping bag close to useless. That is why sleeping on a camp cot without a sleeping mat can also be a surprisingly cold experience. It’s also why some hikers, concerned about weight, use a quilt instead of a bag, on the basis that any of their bag that is underneath them is wasted anyway.

So, a really good sleeping mat which traps plenty of air is vital. No matter how good you think you are at being comfortable on hard surfaces, you need a decent mat simply to keep you warm. The colder it is likely to be, the thicker your want your sleeping mat to be.

I have a Therm-a-rest NeoAir XTherm and it’s without doubt the best camping mat I’ve ever used, keeping me warm even while lying on ground that’s frozen solid.

Hot drink flasks – both insulated and non-insulated

By and large, I’d recommended insulated drinks containers on very cold trips. They’ll keep your hot drinks from going cold, and hot drinks can be literally a life-saver in cold conditions. But they’ll also keep your cold water from freezing, which is just as important.

There is one benefit to a non-insulated flask though – ideally something like a stainless steel drinks flask. Fill it with hot water before you go to bed, then stuff it into a sock, and you’ve got a hot water bottle you can tuck into your sleeping bag with you. It’ll also mean that in the morning you should have some drinking water that isn’t frozen, which is definitely useful.

How do you keep your tent warm inside?

A decent tent will usually do a good job of keeping you dry, reducing wind-chill, and keeping bugs and insects out. They don’t do a particularly good job of keeping you warm, and that’s not really what they’re designed for. Here are a few of the things you can think about to stay warm in your tent in winter, but our advice is to focus primarily on the above items first as your personal sleeping bag, clothing and camping mat will have a much greater impact.

Use the smallest tent possible, and try to fill it up.

Your body heat will warm up the air inside a tent, and the tent fabric will retain that heat to a certain extent. It follows, then, that by having less empty space inside the tent your body has less work to do to keep it warm, and there will be less circulation and movement of cold air replacing the warm air. So, use a tent that is the right size for the number of people (don’t camp solo in a two-man tent, for example) and, if you’re worried about being cold, consider bringing your pack into the tent to fill some of the space rather than leaving it in the vestibule area.

How to insulate your tent.

Because of the additional surface area, insulating a tent will always require more material than simply insulating your own body (with clothes or a sleeping bag) and so is often not very weight-efficient. That’s why we’d see it as the last resort for anyone who is interested in reducing the weight of their pack. However, if you are not hiking long distances, or are staying in one location for several days and want to try to make the tent more comfortable to live in without having to be huddled in your sleeping bag, and especially if you are car-camping, then insulating your tent might be a viable option.

The first thing you should usually focus on is the ground. On a cold day, you will lose heat through the ground much more quickly than through the air, and sitting or lying on the tent floor will be extremely uncomfortable if it is resting on ice, snow, or freezing soil. Additional layers of tarp or groundsheets (often known as a ‘footprint’) may help a bit, but ideally you need something that traps a bit of air and creates space between you and the ground: carpets or rugs, foam mats, or a large inflatable mattress could all work.

The next option is to insulate the upper part of the tent against the air. Foil blankets inside the tent can help to reflect heat and keep it inside the tent, while an additional tarp placed over the whole tent creates another layer of trapped air which will insulate you further.

Can you warm your tent with a heater, stove or candle?

In theory, a small candle can create a surprising amount of warmth in a small area however the risk of fire in a tent is such that we would not recommend this except in a life-or-death emergency situation. We would also strongly advise against using any cooking appliance to heat a tent – both because of the risk of fire, and the potential danger of carbon monoxide poisoning.

In our view, the only safe option is a purpose-designed tent heater. These may run on electricity and require a power link or generator, but some run on gas so they can be used away from power. Nevertheless, they are so heavy that they are not a practical option for most hikers and you will almost always be better off simply packing a heavier sleeping bag, a warmer coat, more hats, or a thicker roll-mat.