Cold weather is common all year in the Arctic and Antarctica, as well as at high elevations, and during winter in temperate areas. Cold weather is part of everyday life for the residents of these areas, as well as travellers who pursue winter sport or mountaineering, or who go for whale watching or to view the Northern Lights.
Cold threatens health by two distinct mechanisms, frostbite and hypothermia.
- Frostbite is a result of freezing of exposed skin and has effects similar to a burn, usually affecting the face, ears, fingers and toes. It can be quite painful and, in extreme cases, can lead to permanent damage.
- Hypothermia is lowering the core body temperature due to inadequate protection from cold, and may occur even in relatively mild weather if clothing is inadequate or if it gets wet. Part of the danger is that hypothermia makes one feel tired and clouds judgement, so victims may sit down, stray away or do other things totally inappropriate for the situation.
Cold weather, in particular hypothermia, is potentially lethal. Someone who falls into water at just above the freezing point and is not wearing protective gear has a life expectancy well under an hour, and longer exposure to less intense cold can also kill; in some cities, homeless people die from hypothermia every winter. In wilderness areas, or anywhere without warm shelter, you need three things to survive – skills, clothing and equipment. A serious deficiency in any of the three can be fatal, though high quality in any one can partly compensate for deficiencies in the others.
Keep in mind that clothing that feels adequate for short walks may be all too cold when you have to stay outdoors for extended periods. Also remember that nights and early mornings may be much colder than the day. With windy, rainy, or snowy conditions, more protective clothing is required. Trying to just "tough it out", which may be possible in warmer climates, can be dangerous.
You should never have to feel cold. Adequate equipment and behaviour will let you feel comfortable and enjoy your stay in all but the most extreme conditions.
Apart from the cold itself, there are also some dangers from the ice and snow. These are discussed under related risks below.
- Det finnes ikke dårlig vær, bare dårlige klær.
- "There is no such thing as bad weather, only bad clothing." — Scandinavian proverb, attributed to Roald Amundsen, first man on the South Pole.
Near and below freezing point, you should cover your entire body. Don't neglect gloves, headwear or scarves. At colder temperatures you should be careful where clothes join, such as at wrists, the waist and the neck; too short a shirt will cool the back and an exposed wristwatch may cause frostbite in extreme temperatures. It is common to choose clothes that overlap considerably, or that include some method of sealing their edges (drawstring, elastic, velcro or fasteners), to alleviate such problems. It's not only cold air you need to protect yourself from, trips into the wilderness often entail hiking or skiing through deep snow — something you don't want inside your boots or trouser sleeves. Some trees like spruces may have low-hanging branches with a great deal of snow on them (making them hang even lower) and an inadvertent light swipe may discharge all of it down your neck and back if you're not wearing a hood. If not removed, snow will melt into literally ice-cold water which will cool you down. If you plan to be outdoors in the cold for longer periods, a warm one-piece garment is often the best solution — it will keep you warmer as heat won't escape as easily and it will also protect you better from snow. The drawback is that they may be less flexible when you want to get rid of excess heat, e.g. when climbing a hill.
Special attention should be paid to clothing babies, children and youth correctly; children need warmer clothes than adults because they have a higher ratio of skin area to weight. The old joke that defines a sweater as "a garment that a child puts on when its mother feels chilly" actually describes a reasonable policy in many cases; children may not clearly communicate discomfort or symptoms, so adults must watch out for them. The cheek and nose of a baby should feel warm also in extreme temperatures. As a rule of thumb, a child needs one more layer of clothing than an adult in the same weather, babies more (but having too much is not comfortable).
Pay great attention to footwear. Boots should be high enough to protect the ankle and for snow not to enter (preferably also protected in other ways). The sole must be thick enough and the boot itself and socks (often a thick pair over a thin one) should be warm. Use removable insulating insoles. The footwear must not be too tight, as that restricts blood flow, essential to keep the feet warm (and lessens trapped air). Near the freezing point boots must be protected from wet snow, e.g. by waxing. Below -5°C moisture is less of a problem, but sunshine may still melt snow on the boots.
Also pay attention to the head; it needs plenty of insulation and good protection from wind. The circulation system is adapted to keep the brain warm, even at the expense of other organs; roughly a third of the blood supply goes to the brain. An unprotected head may not feel cold since the scalp has few nerve endings, but it can quickly drain the body of heat. There is also a risk of frostbite of the ears, which can be very painful. A hood protects the ears and (if extending forward) the face. Scarves or balaclavas make the experience much more comfortable by keeping the neck warm, instead of having to keep the shoulders in a permanent shrug. Long scarves are also handy for covering your nose, chin and cheek when it gets extremely cold.
You also need mittens or gloves; mittens have less surface area than gloves, so they lose less heat. For driving, photography and some other activities, you need to use your hands. It is common to wear a light pair of gloves for that with thick mittens over them to keep the hands warm the rest of the time.
For materials, avoid cotton because it keeps moisture which can contribute to hypothermia. This is especially important for underwear, since if one breaks a sweat, cold and damp cotton feels like being dipped in a pool of cold water. Wool, silk and some synthetics are more suitable. Materials with many small pockets of trapped air — especially duck or goose down and some microfiber synthetics — are ideal, combining light weight with excellent thermal insulation. Down is sensitive to moisture though; when wet it looses its fluffiness (in modern products the down is usually treated to make it somewhat water-resistant). Wool and fur are heavier but they also have insulating air pockets; wool is very good anywhere that it is protected from moisture, and keeps feeling warm also when wet (but becomes heavy and less hardy). It is often used for example in socks, sweaters or a cap worn under a hood. Woolen trousers are better than cotton, but not ideal if they get wet. Also cotton can be used e.g. in anoraks, where it is less likely to become wet (even tightly woven fabric usually breathes enough not to get wet in such use) and it becoming wet is less of a problem.
None of those materials are waterproof or wind-resistant, so you need another layer for that. Fur worn as the Inuit (Eskimo) do — waterproof skin outside, insulating fur inside — sheepskin worn the same way, as many natives of Central Asia and the Caucasus do, or a more conventional parka with a waterproof shell over a warm lining are ideal (but the clothes should "breathe", i.e. allow enough air circulation).
Several layers of clothing are often better than a single warm coat. Usually one should have at least a wind stopping outer layer, a warm sweater for breaks and other clothing as needed. At freezing long underwear (long johns) is advisable, at colder temperatures necessary. Pantyhose (tights) are unsuitable, as they (the tight thin types) make the legs feel warm by stimulating blood circulation in the skin, not by insulating.
The clothing should allow easy adjustments when you enter a windy area or start climbing a steeper hill. You should be able to add or remove layers depending on overall temperature. Clothing feeling warm at -5 °C is probably not at all sufficient at -20 °C (and such a drop in temperature from day to night is not extreme).
It is possible to stay warm with a short jacket and ski pants, provided the waist is well sealed, and that sort of outfit may be required for some activities. However, you could also consider a longer coat. People who spend a lot of time outdoors in the Arctic — such as the Russian Army and various northern tribes — often wear coats that reach well below the knee, and even city dwellers in cold areas often wear coats that go to mid-thigh to protect sensitive areas. For women, an ankle-length wool skirt is surprisingly warm when worn with good boots and stockings, quite likely good enough for an afternoon stroll in town even in the Arctic, though not for really severe conditions.
When staying overnight in a tent, hut or other primitive lodgings you should have clothes that are easy to dry. Boots or gloves with thick linings can be problematic. Carrying spare dry clothing — especially gloves, socks and boot liners or insoles — is a good idea anywhere, necessary on hikes.
The best way to get good equipment is buying it little by little (so that you have time to discover what works for you), with advice from experienced friends or going to speciality shops with good service. A good speciality shop should be able to sell you a complete set of equipment that fulfils your needs, but unless you know what you need, you will probably get unnecessarily expensive gear.
Especially if going for extreme adventures, you should also have some time and advice for learning to know your clothes, both what to take when going out a certain morning and how to adjust them in different conditions.
Food, drinks and rest
Keeping warm requires energy and is much harder when hungry – or tired. Have enough food and enough snack and food breaks.
Raisins or other dried fruits are lightweight and good for instant energy. Fructose pills and some candies are also good. Chocolate, while high in energy, loses its taste when cold. Use these "fast" carbohydrates sparingly though, as otherwise your blood sugar level will be jumping up and down.
More drinking water is needed than in mild weather. Warm drinks, such as tea, coffee or hot chocolate, are also good for the mood. Water or drinks in ordinary bottles will freeze, use thermos bottles and local supplies (e.g. clean snow, if you have cooking equipment) instead, or keep a small bottle in a pocket inside the jacket. Avoid alcohol, as it affects blood circulation in the skin.
Rest is important, as keeping warm is more difficult – and making bad decisions easier – when tired. But when really tired you must not rest until having found safe shelter, as continuing after the rest may be difficult, especially if part of the company is suffering from hypothermia. In such cases, do not let anybody sit down or stay still until the shelter is ready, warm and comfortable. Make sure everybody puts on their rest sweaters also on ordinary breaks.
Moving is essential to keep warm. Especially with children, it is good to encourage games of tag, round dancing, or any physical activity during breaks, before they would otherwise become miserable or even passive. Adults are harder to engage, but often benefit the same way. Such activity should not make people wet with sweat though, and at extreme temperatures breathing gently may be important.
A sauna can be a comfortable way to recover from the cold. Don't get excessively warm, though.
Wind and moisture
Cold weather is much less dangerous when not combined with wetness or wind. Moist air will feel much colder than dry air at the same temperature, and wind will increase the cooling effect and therethrough the frostbite risk.
Adjust labour and clothing to avoid sweating. The worst thing to do is to first get thoroughly sweaty and after this stand/sit/lay still in a cold environment. Avoid having your clothes and shoes get wet by melting snow (or by water). Avoid open windy terrain if you are near your limits. Get shelter for the breaks. Do use your dry spare clothes as needed. Changing clothes may be uncomfortable, but you will feel better soon afterwards. Not changing will leave you miserable, vulnerable to hypothermia.
Cotton fares very badly in cold weather when moist or wet. One should avoid cotton undershirts if exercising and sweating; instead, wool and artificial fibers retain more of their insulating ability when moist. The same applies to socks; woolen socks are better than cotton socks.
Getting drenched at freezing temperatures, as in falling into water, is an emergency. Without a change of clothes or going inside into a warm room, hypothermia quickly sets in. In cold water, useful movement is possible up to 10 minutes and survival up to 30 minutes. However, the immediate cold shock response can make one inhale water or even cause a heart attack.
Cars should be equipped with a cabin air heating system for a comfortable ride and for safety. Moreover, the humidity from occupants breathing tends to frost over the windows, and removing the frost requires flowing warm air. Gas stations sell winter-grade diesel and gasoline in winter; summer-grade diesel may cloud and freeze over. Car engines can be pre-heated with engine block heaters to prevent starting problems. Winter driving is more difficult than summer driving because of slippery roads; the traction is often too weak to permit tight turns at a higher speed than about 30 km/h.
Carry enough emergency equipment in the car to survive if it slides off the road and you need to wait to be rescued (or if thick snow on the road forces you to stop). The most important items are enough sleeping bags to keep everyone warm and some means of emergency communication – cell phone or CB rig depending where you are. Food, beverages, candles and emergency flares are also a good idea. If a vehicle does crash or fail it is almost always best to stay in the car; this provides some shelter, avoids the risk of getting lost, and makes it easier for rescuers to find you.
When biking, snowmobiling or motorbiking, much more protective clothing is required than when walking. The relative wind easily finds its way through gaps and holes in the clothing. Protective glasses, face-covering balaclavas and possibly hard face shields are used. Motorcycle helmets are usually equipped with vents that can be shut for cold weather. However, bike helmets are built for letting the wind in rather than keeping it out, and the cold wind can cause tremendous headaches. Using a tight-fitting warm hat is necessary, and some cyclists tape over the openings in the helmet from the inside.
Few devices are designed for freezing temperatures, even fewer for extreme temperatures. Low temperatures are often accompanied with big temperature differentials (at least when moving in- or outdoors) and condensation caused by these, both of which are much worse for electronics than coldness in itself.
You should not be too dependent on electronic gadgetry, as it is more probable to fail than in normal circumstances. You should also protect valuable or important devices e.g. by carrying them under your outer clothing and let them adjust to the temperature before turning them on. Batteries give more current when warm, so having (spare) batteries in a warm place until needed can help. E.g. a mobile phone can discharge its batteries in quite little time if kept on in a cold environment.
Staying outdoors overnight in freezing weather should be done only with great caution and careful planning, in a shelter, with a good enough sleeping bag and with good insulation to the ground (air mattresses for the beach are worthless, mattresses for hiking not necessarily enough). Everything outside the sleeping bag will freeze.
Most good sleeping bags are nowadays marked with a "comfort" and an "extreme" temperature. At the comfort temperature you are supposed to get a good rest (but conditions and people vary). If night temperatures are expected to come anywhere near the "extreme" point, you will not want to sleep outdoors without fire and good shelter. Remember that most weather forecasts cite day temperatures. A nightcap and good pyjamas might be needed. Also a sheet can make the sleeping bag a little warmer and more comfortable (special silk sheets are sold for the purpose, much lighter than normal sheets).
If you intend to stay the night by a fire, be sure to collect enough firewood before going to sleep and to have a watch all the time. If there are many of you, you can take turns watching the fire. Skill is needed to use an outdoor fire effectively. A cloth can be rigged to protect for wind and snow and reflect the heat from the fire (cf. tarp tents; there are also tent substitutes made for this use). Having it a little sideways to the wind will lessen the effect of it catching smoke from the fire. Snow can be used to seal the gap between the ground and the shelter. A thick layer of twigs between the ground and the hiking mattresses will make the night feel considerably warmer.
When staying overnight indoors, make sure to get shoes and clothes properly dried (without overheating them). Unlike at home, things will not dry automatically in a wilderness hut. Avoid having snow melt on your footwear and clothes. Wilderness huts and mountain cabins often have wood heated stoves for warmth. If intending to use such shelters, make sure you have some experience in how to light a fire with possibly damp firewood (and wood heated stoves in general). The firewood may be outdoors under the eaves or in a separate woodshed. Usually some firewood is indoors, so that you get the fire going, but replenish from outdoors as soon as possible.
If you are away from inhabited areas you must be able to cope with emergencies yourself, at least for some time. Somebody who becomes disabled or wet (stepping through the ice of a river or even a ditch) may soon risk hypothermia.
If lost, you can dig a pit in the snow for protection against the wind. A more elaborate option is building a wall from igloo bricks, which can protect a tent. A snow cave is a good option if you have the know-how, otherwise they are dangerous. If you can choose between open terrain on one hand and forest or other sheltered areas on the other, choose the latter for your camp, even if not in immediate vicinity.
A disabled person must have good insulation from the ground and much warmer clothing than those who can stay warm by moving. You probably have hiking mattresses and blankets that can be used. Sharing a sleeping bag is a very good way of keeping somebody warm (there are also models that allow combining one sleeping bag with another compatible one). You might want to build some kind of shelter (e.g. a big cloth rigged with ropes) and make a fire. In some cases you will have to construct some kind of sledge or travois (e.g. two young trees with a platform between them, carried by the thicker forward end and soft branches left in the other end keeping it afloat on the snow), but usually it is better to have the help come to you.
If somebody gets thoroughly wet boots or clothes, they must be changed without much delay. There might be a house nearby, where you can seek shelter. Otherwise you hopefully have enough spare clothes. Wet boots can still be used by having the foot and warm dry socks in a plastic bag inside the boot. You might want to camp soon to be able to dry the clothes at a fire (which will take a lot of time).
An acute threat of hypothermia is an emergency. Therefore, if exposed and without means of recovery from the situation, one should promptly ask for help, or in the absence of other means, seek shelter by any means necessary, not wait for the situation to get worse. In the event of getting lost in a foreign city at night without warm clothes or a cellphone, one should contact emergency services or anyone nearby, not wander around until hypothermia clouds the consciousness. It is especially important to tell youth and children to not wander around if they get lost, but contact an adult immediately.
Frostbite and hypothermia
There are two dangers in cold weather: frostbite and hypothermia.
Frostbite means damage caused to skin and other tissues due to freezing. Although the mechanism is different, the effect resembles burns, and like sunburn, the condition might not get noticed until too late. This is especially true during physical activity such as trekking, or in windy weather. In theory, cooling the skin is painful, but cooling also lessens sensation. It is easy to ignore the beginnings of numbness, and then damage can occur unnoticed. Therefore awareness and active checking are needed. Watch out for white spots on your fellows' skin. The nose, ears, chin and cheek are the body parts most easily affected, especially in windy weather. Fingers and toes may also get frostbitten, but you will more easily notice them getting uncomfortable. Also, touching metal surfaces with bare skin can cause frostbite.
First aid in the field may include gently warming the affected area with a warm body part, for example putting cold fingers into the armpit or putting a warm palm over a cold nose. The main thing, though, is to protect affected areas from the cold so the frostbite will not get worse. Frostbitten skin is vulnerable to burns and frozen nerve endings will not report a problem; be very careful if warming up at a fire.
Once in warm shelter, you can just let frostbitten parts thaw naturally or assist the process by putting them in lukewarm or tepid water. Be prepared for some discomfort; thawing out a frostbitten part is often more painful than getting the frostbite. Do not use hot water; this both increases the pain and risks further injury to the skin. Consider having a glass of brandy or some such to dull any pain that may appear.
Hypothermia is overall reduced body temperature. It will lead to loss of initiative, sluggish thinking and irrational behaviour. Keeping on walking even when tired is important, not only to reach shelter, but also to keep warm. If you are trying to assist a hypothermia victim, you can usually get them to come with you provided they are still on their feet, but getting somebody to rise and start walking is much more difficult. In severe cases it is important to warm the victim slowly, without massaging, because cold blood from arms and legs may cause vital organs to fail.
Sensitivity is highly variable between individuals: people with particularly good peripheral circulation may feel perfectly comfortable in -20 °C with thin gloves and a single-layer jacket, while others may need mittens on gloves and multiple layers of clothing. The elderly, the disabled and children are more vulnerable to frostbite and hypothermia. Another factor is how used you are to cold environments. Children might try to lick a metal rail or another surface, which instantly freezes the tongue, and the usual response, jerking back, tears off the frozen part of the mucous membrane, resulting in a bleeding wound. Many children in cold countries have tried this once, but not twice.
Where there is cold weather, there is usually snow and ice, which in themselves can pose some risks.
The most common cause for accidents in winter is slippery roads, pavements (sidewalks) and especially steps. At a minimum, you need footwear with suitable soles. Sometimes add-on equipment, such as tire chains on cars or devices like those in the photo, may be used to prevent slipping. Sand, gravel or salt (calcium chloride) is often scattered on roads or paths to improve traction.
In slippery conditions it is generally advisable to do a "penguin walk" with very short steps rather than the longer stride used in other circumstances. This reduces the tendency to slip because there is less horizontal force where the foot meets the ground. Also, if one foot does slip, your chances of recovering without a fall are better because your center of gravity is more nearly above the leg that still has traction.
Even moderate snowfall – or wind causing snow to fly around – will reduce visibility substantially. It will also cover your trail in little time. In open landscape, like on mires, lakes and fell heaths, you will need some way to keep a course accurate enough to find shelter. Really thick snowfall can make it difficult even to find the route across a yard.
The snow will often hide dangers, such as cracks in the ice and clefts in the rock, or give the impression a cliff extends farther than it does.
In mountainous terrain avalanches are a real risk. Always use local warning services.
Even in town, falling ice or snow can be a serious danger. In particular, icicles may come off the edge of a roof and hit pedestrians below, and a heavy chunk of ice dropping several storeys is easily fatal. Note that ice sliding off the roof will hit the ground quite some distance from the wall, avoiding falling icicles is not enough.
- Main article: Ice safety
The frozen sea, lakes and rivers may be inviting. A number of activities on frozen bodies of water – skating, snowmobiling, ice fishing and ice boating – are fairly common. During prohibition, bootleggers even ran truckloads of booze from Canada into the US across the frozen Saint Lawrence; those were quite heavy but reasonably safe with two meters of mid-winter ice. However, always seek knowledgeable local advice on which areas are safe. The ice may be thin or otherwise unreliable in some areas, even when thick in general. If the ice breaks, it is hard or impossible to get out without tools or assistance. Purpose-designed ice climbing picks, worn on a sling around the neck are sold to ice fishers.
There may also be substantial dangers from the sheer speeds involved in some modes of moving. An ice boat is far faster than a normal sailboat, because of the low friction, and a good skater is much faster than a runner, but if you fall ice is as hard as concrete. Skiers and snowboarders do not have to worry about the hardness of ice, but they also move fast enough that any mistake can cause serious injury.
Have fun! Skiing, snowmobiling or snowshoeing in an Arctic night, with northern lights shining, is an unforgettable experience. Furthermore, whole modern societies live and work in cold climates, including children, the elderly, and the disabled. Winter or snowfall is barely an obstruction, with life in the society continuing normally. Taking some simple precautions and not being foolish is all that is necessary for a traveller.