harsh snow winter environment

36.5, its at the Core of our survival

So what is my biggest concern in regards to survival in the Northern Hemisphere?

The cold. After dealing with any medical issues this must be next on the agenda. The human body is actually very tough. It can withstand a lot of abuse and punishment, what it can not deal with however is a significant change in its core temperature.

Most humans core temp is 36.5 degrees celsius. If this drops below 35 degrees we will be in the midst of hypothermia. In a very short period of time we will die.

That’s only 1.5 degrees! So how do we prevent this. Well we have a few options.


When most people think of shelter they imagine a tarp, a tent, maybe even a cabin. However, we must remember that our primary shelter are the clothes we are stood up in. These must be adequate for the conditions. Plenty of layers so we can regulate our temperature so as not to sweat. If you sweat, you die. Sorry, I’m being dramatic again.

This is true though. If you sweat you get wet, then you get cold, when you stop you get very cold. Our clothing MUST NOT BE COTTON. Cotton kills people when it is wet. Honestly, you would be better in your birthday suit than in a wet cotton one. Add some wind and it will super chill you. You must be able to stay dry.

Fast drying technical clothing or 100% wool and a waterproof layer are a must. Dress for success and when you walk out through the front door ask yourself this, could I go and sit in the woods, next to a fire, overnight, in the clothes I have on?

Building shelters are for courses and fools who were not prepared. Always carry shelter, there is no excuse in the modern world with plastic and silnylon tarps.

We need three things

  • Something to sleep on
  • Something to sleep in
  • Something to sleep under

We lose heat in three ways: conduction, convection and radiation.


Conduction is the big one people forget. Laying on the cold ground will kill you. The earth will literally suck the life from you as you sleep. We must put something between us and the ground.

Roll mats and inflatable pads are great for camping, but we just can’t carry these all the time. I am a big fan of the big orange bivvi bag. This is NOT to be entered. It is to be filled with debris such as leaves, bracken, grass etc. We then tie a loose knot in the top and use it as a mattress. It is very light and very effective.

If we must build a raised bed it must allow a “limit of advance” so it can’t be crushed and flattened while we sleep. By laying sticks on the ground and making a platform which is then padded with leaves etc we can raise ourselves inches if not feet from the ground.

When I spend time in an arctic environment I will even split wood and stand on it to alleviate conduction with the frozen ground. Every little bit helps, and I hate cold feet!


This is basically the effect of the wind removing your warmth. I also consider precipitation in this category. We must have something to sleep under.

My little tarp weighs just under 400g and is big enough for 2 people. No excuses. Now we could build a shelter. I teach this in my courses. I also teach the fact that it takes at least 3 hours to build something that is up to the job, and that is if you have the materials. A poncho is a very good option. It can be worn and used as a tarp. They are also cheap. Go for a good make such as Helikon or DD Tarps, not the one you bought at the music festival!

dd tarp 3x3 Pro
DD Tarp Pro (photo: ddhammocks.com)


Something to sleep in so we don’t lose our body heat. Again, carrying a sleeping bag with you is just not an option for an unplanned night or 2 in the woods. We do have other very good options.

Blizzard is a company that makes a range of emergency products. The bags and blankets are outstanding and are issued to the military for keeping casualties alive.They are made of Mylar and are a concertina style design that allows heat to be trapped in dead air space.

I have used the bags and the blankets and find they are similar to using a mid weight sleeping bag of around TOG7. I no longer carry the bag though. It is very difficult to put a casualty into a bag, where it is much easier to wrap them in a blanket.

So that is my shelter system; in the winter I add a GoreTex bivvi bag and a warm layer. The whole kit weighs in at 400g for the tarp, 430g for the blizzard blanket and 300g for the orange bivi bag. That’s a total of roughly 2.5 pounds and will save my life.

Emergency blanket protects against the cold
Blizzard Emergency Blanket (photo: blizzardsurvival.com)


An external heat source may well be vital. This is not an option in some settings such as in the mountains, however, we must have the ability to light one. Carry the means along with tinder.

Heat packs are very handy. Some very good and cheap options include the pads used to transport tropical fish and snakes. Much cheaper and they last 18 hours. Top tip.

You can also warm rocks by the fire and cuddle them. I have a friend who swears by it for keeping his feet warm!


Food is fuel. The body needs calories to burn so in cold weather I will always eat more to allow for this. When operating in Sweden during the winter (-30C) I observed a member of the group pull a solidly frozen ration pack from their pack. You could have banged a tent peg in with it. Carry dehydrated food that won’t freeze!


A double edged sword. Move too much and you sweat, not good. Don’t move enough and you get cold. Find the balance and keep moving. They say firewood warms us three times. Firstly collecting it, secondly processing it and thirdly burning it. Do a few press ups in your sleeping bag if you’re struggling, just make sure you take your arms out first.

So in conclusion

Carry shelter, don’t touch the ground, dress for success, never wear cotton, don’t sweat and keep moving.

Respect the environment, people die every year of hypothermia and exposure in the UK. Don’t be a mountain rescue statistic.

Survive and thrive!