Hypothermia Prevention
Photo by Dave Moskowitz

Hypothermia Prevention

Hypothermia is an extremely serious concern for all outdoor enthusiasts and hypothermia prevention is critical. Once we didn’t recognize it as anything more than an inconvenience and felt it was just a hardship to be overcome. We just bundled up and pushed through it. If you got cold, you just kept it to yourself. Outdoor activities where for men and you had to be tough!

Hypothermia prevention

Today’s miracle fabrics are much lighter and warmer than anything we had. Many modern fabrics make keeping dry and warm easy, but you still must use care and a good bit of common sense. If you planning on enjoying your favorite outdoors activity, you probably do not intend to risk your life, but going into the wilderness unprepared is taking an unnecessary risk.

Hypothermia may be a new word to you. It describes the rapid, progressive mental and physical collapse accompanying the chilling of the inner core of the human body. Hypothermia is caused by exposure to cold, aggravated by wet, wind, and exhaustion. It is the number one killer of outdoor enthusiasts.

We used to call the effects of hypothermia “dying of exposure” or “freezing to death”, but the end result was the same. The unwary didn’t get to go home.

Hypothermia isn’t only a concern for outdoor enthusiasts. Households with elderly occupants over 65 should keep the thermostat set at no less than 68 degrees in the daytime. The problem with low household temperatures is that older and ailing persons are particularly susceptible to accidental hypothermia which can be a life-threatening condition.

Accidental hypothermia can occur even with temperatures of 60 to 65 degrees. Infants less than one year of age should never sleep in a cold room and should be provided with warm clothing and a blanket to prevent loss of body heat.

Warning signs of hypothermia in adults include shivering, confusion, memory loss, drowsiness, exhaustion and slurred speech. Infants who are suffering from hypothermia may appear to have very low energy and bright red, cold skin

If you know of an elderly or ailing person who lives alone, be sure to check on him or her every day.

Frostbite is another cold weather concern and is especially dangerous because it often happens with little warning. Numbness can occur so quickly that the individual, unaware of being frostbitten, may remain

Winter Danger

Cold weather can kill in two distinct steps, through exposure and exhaustion. When your body begins to loose heat faster than it can produce it, you are undergoing exposure.

You can do two things:

  1. You can voluntarily exercise to stay warm. We did this a lot, but there’s a trade off. Eventually, you will become exhausted and be unable to continue vigorous enough exercise in order to keep warm. OR
  2. Your body makes involuntary adjustments to preserve normal temperature in the vital organs, and you start shivering.

Either response drains your energy reserves. The only way to stop the drain is to reduce the amount of exposure.


If exposure continues until your energy reserves are exhausted:

  • Cold reaches the brain depriving you of judgment and reasoning power. You will not realize this is happening.
  • You will lose control of your hands. This is extremely serious. You may be unable to light matches. You may take off your gloves or mittens and be unable to get them back on. You may even find you can’t zip up your jacket or sleeping bag.

This is hypothermia. Your internal temperature is sliding downward. Without treatment, this slide can lead to stupor, collapse, and death.

Steps To Follow for Hypothermia Prevention

1. Avoid Exposure

STAY DRY. Wet clothes lose about ninety percent of their insulating value. Wool loses less. So do some of the new synthetics. Cotton and wet down are virtually worthless. Check the insulating values of the materials you choose to wear.

STAY OUT OF THE WIND. A breeze carries heat away from bare skin much faster than still air. Wind drives cold air under and through clothing. Wind cools wet clothes even faster by evaporating moisture from their surface.

WIND MULTIPLIES THE PROBLEMS OF STAYING DRY. If you have been in water and you are wearing a T-shirt that is wet, take it off. You will stay warmer. Direct sunlight on the skin also helps the warming process.

UNDERESTIMATING EFFECTS OF COLD. Most hypothermia cases develop in air temperatures between 30 and 50 degrees. Most outdoor enthusiast simply don’t believe such temperatures can be dangerous. They underestimate, often with fatal results, the danger of being wet at such temperatures.

Fifty degree water is unbearably cold. The cold that kills is cold water running down your neck and legs, and cold water removing body heat from the surface of your clothes.

HYPOTHERMIA IN WATER Loss of body heat to the water, is a major cause of deaths in boating accidents. Often the cause of death is listed as drowning; but, often the primary cause is hypothermia. Alcohol also lowers the body temperature around two to three degrees by dilating the blood vessels. Do not drink alcohol around cold water.

The following chart shows the effects of hypothermia in water:

Water Temperature

32.5 degrees
32.5 to 40
40 to 50
50 to 60
60 to 70
70 to 80
Over 80


Under 15 min
15 to 30 min
30 to 60 min
1 to 2 hrs
2 to 7 hrs
3 to 12 hrs

Survival Time

Under 15 to 45 min
30 to 90 min
1 to 3 hrs
1 to 6 hrs
2 to 40 hrs
3 hrs. to indefinite

2. Terminate Exposure

If you can not stay dry and warm under existing weather conditions using the clothes you have with you do whatever is necessary to be less exposed. Find some sort of emergency shelter from the elements and make a fire.


Get out of the wind and rain. Build a fire. Concentrate on making your camp or bivouac as secure and comfortable as possible. SAFETY FIRST.


Persistent or violent shivering is a clear warning that you are on the verge of hypothermia. MAKE CAMP OR GET BACK TO YOUR VEHICLE.

3. Beware of Exhaustion

Make camp while you still have a reserve of energy. Allow for the fact that exposure greatly reduces your normal endurance. You may think you are doing fine when the fact that you are exercising is the only thing that is preventing you from going into hypothermia.

If exhaustion forces you to stop, however briefly:

  • Your rate of body heat production instantly drops by fifty percent or more.
  • Violent, incapacitating shivering may begin immediately.
  • You may slip into hypothermia in a matter of minutes.

4. Appoint a Leader

Make the best protected and experienced member of your party responsible for calling a halt before the least protected member becomes exhausted or goes into violent shivering.

Don’t make the mistake of appointing the most macho member the leader. Make sure your leader has the common sense to look out for the welfare of all of your party members.

5. Detect Hypothermia

If your group is exposed to WIND, COLD, OR WET, start thinking about possible hypothermia, even if it’s a comparatively warm day. Remember that most hypothermia cases develop in air temperatures between 30 and 50 degrees. I’ve mentioned these signs before, but they can’t be emphasized enough. Watch yourself and others for these hypothermia symptoms:

  • Uncontrollable fits of shivering.
  • Vague, slow, slurred speech.
  • Memory lapses, or incoherence.
  • Immobile, fumbling hands.
  • Frequent stumbling.
  • Drowsiness (to sleep is to die.)
  • Apparent exhaustion. Inability to get up after a rest.

The most important thing to remember about cold weather camping is to KEEP DRY. Moisture will reduce the insulating properties of almost everything. To keep yourself warm, remember the word COLD.

C. Keep yourself and your clothes Clean. Clean clothes have a greater insulating value

O. Avoid Overheating. Try to avoid perspiring.

L. Wear clothes Loose and in Layers. Layers trap pockets of air adding insulating value.

D. Keep Dry. Wet clothes loose up to ninety per cent of their insulating value. If your clothes become wet, change clothes or dry them immediately!

CLOTHING TIPS for hypothermia prevention
  1. Layer your clothing. Wear several layers of lighter, loose clothing instead of one heavy layer. This way you can better regulate the amount of insulation. If you get warm, take layers off. Add more clothing layers if you get cold.
  2. Keep dry. Avoid wetness from weather and perspiration.
  3. Remember when buying clothes for cold weather that wool retains most of its insulation properties, even when wet. Check the insulation value of all materials bought for cold weather use. There many excellent man-made fibers and insulation’s that retain their insulation properties as good as or better than wool. Other benefits include light weight, wide design options & wind-blocking.
  4. Remember your rain gear is water proof and will not allow perspiration to exit. During rainy weather change your clothing several times a day. You’ll get as wet under your rain gear from perspiration as you would have gotten from the rain. Many times I’ve gone without the rain gear during warm rainy days when I was moderately active and only put on dry clothing and rain gear when I stopped all activity.
  5. Athletic shoes and nylon hiking boots do not provide enough insulation. You should wear either mukluks, water-proofed leather hiking boots, rubber overshoes or rubberized boots. Cold feet can make for a miserable day and lead to trench foot and other cold weather problems. Make an effort to keep your feet dry.
  6. Waterproof your leather hiking boots with the appropriate commercial treatment. Be sure to use only silicon-based products on leathers which require it. Check the care tag that came with the boots. This is no guarantee that you’ll keep your feet dry if you step into pools of deep water. Try to avoid water that may flow into your boots, especially if you don’t have dry boots to change into.
  7. If you choose to wear rubberized boots, remember they do not allow for ventilation. You will need to change your socks several times a day. Also you may want to get some felt inserts for insulation.
  8. Wear a pair of cotton and a pair of wool socks to increase insulation and take the perspiration way from your feet. It’s a good idea to plan on changing socks several times a day. This keeps your feet warm and dry. Generally, it just feels good.
  9. Pull trouser legs over top of your boots or socks to keep out snow. You may want to use nylon gaiters (leggings), or tie or tape them to seal out the snow and cold.
  10. Wear mittens instead of fingered gloves when you do not need independent use of your fingers. This will allow the fingers to help keep each other warm. I use a pair of woolen gloves inside a pair of “bear claw” mittens I brought back from Antarctica many years ago. They are similar to snowmobile mittens and reach all the way up to my elbows. I can’t do much with them on, but my hands stay warm. As a former frostbite victim, this is important. When my fingers get cold, they hurt.
  11. Use a pair of socks to cover hands if your mittens or gloves get wet.
  12. Wear a stocking cap or other warm hat. Wear a hat that covers your ears and neck. Remember, most heat loss is through the head. Wearing a warm hat warms the rest of your body, too.
  13. Look for a parka with a hood that extends several inches beyond your face and will form a pocket to protect you from wind and blowing snow. My favorite parka extended about a foot past my face and could be shaped to close into a narrow slit allowing only a narrow opening for vision. Of course, I didn’t wear this along busy highways or in areas were I needed to be able to see were I was going, but in heavy, blizzard conditions it provided great protection!
  14. Wear a scarf to reduce heat loss around the neck. Use a “ski mask” or scarf over your face for protection from the cold and wind.
  15. Paper is a good insulator and can be wrapped around the body (under your clothes) to add insulation. In an emergency, leaves, grass, pine needles, etc. also work well.
Bedding Down
  1. Natural fiber sleeping bags do not maintain their insulation properties when damp. Try to air your sleeping bag daily and avoid allowing the insulating material to becoming compacted.
  2. A 3 to 4 pound synthetic bag will take care of most of your needs.
  3. A mummy style bag is warmer than a rectangular, as there is less space for your body to heat. Also, most mummy bags have a hood to help protect your head.
  4. Whatever type of sleeping bag you use, a ground cloth is always a good idea to prevent ground moisture from making your bag damp at night. Your body heat will thaw any moisture frozen in the earth.
  5. Do not sleep with your head under the covers. Doing so will increase the humidity in the bag from your breath. This will reduce the insulation properties of the bag.
  6. Remember to air out your sleeping bag and tent, when weather permits. Perspiration and breath condense in the tent at night and the water will reduce insulating properties of your bag.
  7. Wear a stocking cap to bed in order to reduce heat loss.
  8. Wear a loose fitting hooded pull over type sweatshirt to sleep in.
  9. Make a loose fitting bag from an old blanket or carpet padding to put both feet in when in your sleeping bag.
  10. A bag liner made from an old blanket, preferably wool, will greatly enhance the bags warmth.
  11. Insulate yourself from the ground as much as possible to avoid cold spots at the shoulders and hips. I like pine branches and piles of leaves. They make good padding, too.
  12. Use a sleeping pad of closed cell foam instead of an air mattress. I learned the hard way that an will air mattress not only leak, it will get cold.
  13. A good rule of thumb is that you want 2 to 3 times the insulation below you as you have over you.
  14. Cold air will be above and below you if you sleep on a cot, so you will need extra insulation.
  15. Put a hand warmer (in a sock) at the foot of your sleeping bag before getting into it. A canteen with hot water (not boiling) and placed at the foot of a bag to keep warm works. Be careful with plastic canteens. They might leak. (Also be careful of a tent full of enlisted men observing the ole Sarge putting a hot water bottle in his sleeping bag. Awful hard to explain.)
  16. Exercise before bedding down to increase body heat. This will help to warm your bag quicker. Be careful not to start perspiring.
  17. Remove the clothes you are wearing before. Put on dry clothing or pajamas before entering the sleeping bag.
  18. Build a wind break outside your tent by piling up snow or leaves to a height sufficient to protect you when lying down.
  19. Hang your sleeping bag up or just lay it out, between trips, so the filling will not compress and lose its insulating properties.
  20. Before you get out of bed bring the clothes you plan to wear inside your bag and warm them up some before dressing.

Hypothermia Prevention ODDS AND ENDS.

  1. Organization and proper preparation is very important in cold weather camping. Good meals, proper shelter and comfortable sleeping arrangements make for an enjoyable outing.
  2. Drink 2 quarts of fluids per day besides what you drink at meals.
  3. Learn to recognize and treat cold weather health problems. These include frostbite, hypothermia, dehydration, chilblains, trench foot, snow blindness and carbon monoxide poisoning.
  4. Use the buddy system to check each other for cold weather health problems.
  5. If you feel cold, gather some wood or do some other type of work. Working will help warm you.
  6. Eating ice or snow can reduce your body temperature and it is not pure. Don’t eat it. Snow and ice can be used for drinking water but only after boiling.
  7. No open flames (candles, matches, etc.) inside the tents. Wiggling your toes inside your boots will help keep feet warm
  8. Take and wear dark sunglasses if snow is in the forecast. The glare of the sun off the snow could lead to snow blindness. The sunglasses will reduce the glare.
  9. Use the solid fuel hand warmers.
  10. Keep off ice on steams, lakes and ponds.
  11. It takes longer to cook food in cold weather, so plan accordingly. Before going to bed pour enough water for breakfast into a pot. It is easier to heat the pot than a plastic water can.
  12. Keep your matches in a metal match safe as plastic can freeze and break if dropped.
  13. Gather twice as much fuel as you think you’ll need for fires.
  14. Carry tinder from home. It may be hard to find in snow or wet conditions.
  15. Gather your wood and tinder for the morning fire in the evening so that you will be able to start the fire quickly in the morning.
  16. Space blankets make good wind shields only. The metallic properties take over the insulation properties in cold weather and become cold conductors.
  17. Carry extra plastic bags in cold weather. They can be used as personal wind shields and ponchos by slitting a hole in the top for your head to go through.
  18. Carry extra matches because the more you need a fire to warm up the less likely you will be able to start one easily.
  19. Flashlight batteries are affected by cold. You can revive a dead battery by warming it up near the fire.
  20. You may want to take a bottle of propane into your tent with you at night. This will keep it warmer and make it easier to light your stove for breakfast.
  21. Heaters inside your tent can lead to carbon monoxide poisoning.

Winter can be a time of unusual beauty in the wilderness, but it also presents many hidden dangers. Make sure you are prepared to face every challenge and are aware of the danger of hypothermia and never venture into the wilderness without your wilderness survival kit of at least a knife, matches and a signaling device. Knowing hypothermia prevention is a matter of life and death.