Staying warm while camping in the winter is clearly important. Even here in Kent temperatures can get relatively low (OK, if you’re in Canada or Sweden reading this, then temperatures of -5°C might seem positively tropical, but it’s still plenty cold enough to cause problems for the unprepared); indeed, the first ever course we ran saw night time temperatures of -12°C, an experience that brought into sharp focus the fact that I was no longer just responsible for my own wellbeing, but also for that of our customers. These are the hardy souls that braved the weekend (Tim, 3rd from left, is still a regular).
I wrote a post way back in 2013 where I talked about winter clothing for bushcraft, with emphasis on staying warm and dry. In that post I described the layering system and why it’s useful. It might be an idea to take a quick look as the principles of the layering system can be applied to staying warm at night.
Staying warm during the daytime is straightforward, you’re probably going to be active, you’re likely to be consuming hot drinks and food and you might have a fire going to either sit in front of or stand next to as well. So often it’s the night time when staying warm can be an issue. So this post is essentially the advice that we give to our students when we’re running overnighters in the colder months.
How you produce heat
It’s worth remembering that your sleeping bag, much like your clothing, isn’t capable of producing any heat; the heat is generated by your body and your sleeping bag captures that heat and stores it.
At this point it’s worth understanding how our bodies produce heat. In essence it happens in two ways:
- Eating (actually digesting what’s been eaten) and
So, if you’re cold, you need to do at least one of those things to warm up again, depending on your circumstances.
Which sleeping bag?
A big part of staying warm at night in the colder months is going to be the quality of your sleeping bag. I’ve always found the ratings given on sleeping bags to be optimistic, but that might be because I tend to feel the cold.
In broad terms you’re going to be faced with a choice between a synthetic (that is, manmade) or a down sleeping bag.
Down sleeping bags tend to be smaller and lighter but are often more expensive and if they get wet can lose much of their insulating ability. Synthetic sleeping bags tend to be bigger, heavier, cheaper and retain some of their insulating ability if they get wet.
Also bear in mind the provenance of the down being used; I only use ethically sourced down.
You could do worse than an ex-army sleeping bag, they tend to be inexpensive if somewhat bulky. Or you could put one sleeping bag inside another.
Tips for staying warm while camping in the winter
Whilst I’m writing this with either staying in a tent or being under a tarp in mind, most of it is also appropriate for spending the night in a debris shelter. Of course, a lean-to debris shelter gives the advantage of allowing a long fire next to you, keeping you toasty warm.
Going back to the layering system, we can translate it from clothing to sleeping. The simplest example is probably bivvy bag (outer layer), sleeping bag (mid layer) and sleeping bag liner (base layer).
But we need to do a bit more than just that. A major source of heat loss (see this post on methods of heat transfer) is through conduction to the ground. The ground will literally suck the heat right out of you. The purpose of a roll mat isn’t so much to provide comfort as it is to prevent heat loss. So in the winter I use a foam mat and a self-inflating mat with the foam mat closest to the ground and then the self-inflating mat on top of that.
This is my winter set up: bivvy bag, foam mat, self-inflating mat, sleeping bag and liner.
A note on foam mats. There are two kinds of foam mats, broadly speaking; closed cell and open cell. An open cell mat is the kind of thing you would use for yoga. They tend to be porous and soak up moisture. They also are often bigger and heavier but tend to compress more. A closed cell mat is a much better bet for bushcraft.
You could lay a mylar blanket down first, or a foil backed beach mat. Of course, you could use lots of vegetation, but make sure that it’s dry and that you source it sustainably.
There’s an old saying that a blanket underneath is worth 2 on top and this is true. Because you’ll lose more heat to the ground than to the air, you’re better off putting a blanket underneath you as opposed to on top. We have spare blankets that we lend out if students are cold or worried that their sleeping bag might not be up to it and it can sometimes be surprisingly difficult to get them to accept this simple bit of advice.
Another piece of advice that isn’t particularly intuitive is around not wearing all of your clothes to bed. This is important for at least two reasons;
- If you have all your clothes on it’ll stop your sleeping bag from doing its job, that is capturing and storing your body heat.
- You sweat during the day and your clothes will be damp, which in turn will cool you down. So make sure that you wear different clothes to bed than you’ve been wearing during the day, this is especially true of socks, always wear separate bed socks. Typically I go to bed in bed socks, pants and a merino wool base layer.
Get your sleeping bag out of its stuff sack half an hour or so before you intend to get in it. This is to give it time to ‘loft’, that is for the insulation fibres inside to expand so that they can do their job.
Make sure that your bladder is empty before turning in. A couple of pints of liquid sloshing around inside you will cool down quickly and lower your core temperature. Your body will want to eliminate it and so you’ll wake up and have to get up to wee. I generally drink lots during the day and nothing for a couple of hours before I go to bed.
Make sure that you’re warm before you get into bed. Ordinarily people tend not to eat before turning in for the night but as eating is one of the two ways our body can produce heat, it’s worth considering for cold weather camping.
Exercise either immediately before getting in your sleeping bag or whilst you’re in it, the latter could be just a matter of getting undressed in your sleeping bag. Generally I go for the former (squats work well), then take off my trousers, change socks and and get my legs in and then do my top half. In the morning when I’m getting up I do the reverse.
Whilst a hot water bottle might not sound very bushcrafty, using one can make a massive difference to your night. I often use one when it’s cold and pop it into my sleeping bag ten minutes before I get in. If you have a metal water bottle, you could use that but make sure you put it in a fabric container of some sort, maybe a sock, to make sure you don’t burn yourself.
If your sleeping bag has baffles around the neck, pull them tight to reduce heat loss and wear a hat.
If you wake up feeling cold, you can either lay there feeling sorry for yourself or do something to improve your situation. First thing to try is doing some exercises whilst you’re still in your sleeping bag. If you’ve ever done pilates you’ll know there are a whole bunch of exercises that you can do in the same place – think leg extensions and leg raises.
If that’s not enough, get up and exercise, run on the spot, do squats, essentially exercises that engage big muscle groups.
If the weather allows, air out your sleeping bag and liner during the day as they will have become damp overnight.
Hopefully there’s somethng there that’ll prove to be useful when you’re camping in cold weather. Post any of your own tips in the comments below.