If you live in the American Redoubt or any of the Northern US, you deal with a lot of cold winter weather. But all of those folk living in warmer places, you need to take heed too, because cold weather can touch you too in a survival situation. In January 2010, Florida experienced temperatures in the mid-30 degrees Fahrenheit (F) range, cold enough to kill the unprepared individual.
I grew up in Alaska, and spent my childhood and teen years exploring the woods and the mountains, often far from any trails. Winter is actually the optimum time for travel in places where there are no roads and trails because Alaska's dreaded thickets of Sitka Alder and Devil's Club are safely buried under many feet of snow and the streams and rivers are frozen. More importantly, large loads can be sledged behind snow machines (snow mobiles for you lower 48ers), dogs, or humans. The first general store in my hometown was actually brought up the frozen river over 75 miles from the ocean this way back in the early 20th century.
For the purposes of this discussion, I am going to define cold weather conditions as temperatures below 32 degrees Fahrenheit. I am going to exclude another very dangerous condition that is common to the Pacific Northwest- the wet cold when there is liquid water just above 32 Fahrenheit (F).
You may scoff at cold temperatures, even sub zero temperatures. After all, you can go work all day outside in the winter when it is -10 F and still be fine right? You haven't experienced cold weather until you have went out and lived in it for a few weeks at a time. It takes on completely new dimensions when you don't have a ready supply of clean, dry clothes and warm shelter to go back to at the end of the day.
For the newly initiated: No cotton in the cold weather ever! As cotton becomes moist from your sweat, it will begin to take heat away from your body, resulting in hypothermia. Layering is the key to dressing for the cold. You always want to minimize the amount of sweat you produce by optimizing your layers. As you become more active, take layers off. As you slow down, put layers on. Aim for a perfect fit for your layers, but if this is not possible, get clothes that are looser rather than tighter. The air between the layers will help insulate you.
In our active state, we can resist the cold well. That's why you can go outside and work in the cold weather and be none the worse, even wearing light clothes. But as soon as the activity stops, our metabolism drops, and we are at risk of hypothermia. When you are walking, carrying a load or working in cold weather, your clothing can actually be pretty light. On my cold weather running workouts when temperatures were at -15 F, I would typically wear wool socks, poly propylene top and bottom underwear, fleece pants and jacket, balaclava, and thick gloves.
You will be able to turn up some of the items you need at REI or your local outdoors store. But beware: some mountaineering/skiing type clothing is not made with the durability necessary for work or moving through thick brush. Gear made of materials such as thick nylon and wool will be heavier, but you can ill afford to rip your clothes during a survival situation. Duluth Trading Company, Canada Goose, Woolrich, and military surplus all offer the durable, warm clothes you will need. Also, I love my Carhartt gear, but leave it at home for the winter trek. As far as I know, all of their clothes are made to be worn for the day and dried out at night, an option that will not be available to you on multi day trips.
Start with your base layers. I recommend Under Armor brand boxers. One pair per day if possible, just like Mom told you. Thick, high quality wool socks are a must. It might hurt to shell out $20 for a pair of socks, but it is worth it. One pair of socks per day, and always one clean dry pair to wear into the sleeping bag at night. Wear top and bottom long underwear. I have had the best luck with polypropylene long under wear as they keep you very warm even when damp. Generic brands are readily available.
Now we move up into insulating layers. I have a wool union suit that is excellent, but military surplus thick polypropylene "Extreme Cold Weather System" underwear work as well. If I need additional layers, I prefer my light but very warm alpaca sweater. Wool and fleece sweater/jackets are excellent as well. Remember that as you move up in layers, you will need larger sizes to fit over your other layers.
For outer layers, I wear wool pants and a wind breaker. I have nylon overalls for working. For times when you are inactive, you need a heavy down parka with a hood. Don't skimp on the parka! Your parka is probably the single most important clothing item discussed here. For temperatures less than -20 F, you may need down pants as well. I recommend using suspenders or bib overalls as much as possible. When working and traveling it can be irritating to have too many layers going on at your waist.
Footwear should be bought slightly large so that you can wear two pairs of wool socks if needed. I wear thin Smartwool liner socks, thick wool socks and Baffin brand boots. A quality pair of gaiters is an excellent investment, the only brand I have found that works well is Outdoor Research. Whatever brand of boots you get, removable liners are a must so that you can wear them into the sleeping bag if necessary. Your boots will collect a lot of moisture and can freeze solid at night. To rest your tired dogs at night, get a pair of down camp booties to wear around camp.
If your hands are uncovered, they can become numb in less than a minute. Recently, I discovered that by wearing wool "hobo" gloves without finger tips, I could take off my bulky overmitts to do delicate work for a few minutes without making my hands too cold. The military issues over mittens with a trigger finger for operating a firearm, but I have not tried these. If you need more dexterity for longer periods, I recommend a pair of high quality technical mountaineering gloves.
The arctic sun's glare can cause snow blindness after a few days of travel, so you will need tinted goggles. These will also be necessary to protect your eyes from blowing snow in storms.
Head wear is of critical importance because up to 80% of the body's heat can escape through the head. The balaclava is one of the most versatile, useful clothing items for cold weather survival. It can be used as a hat, scarf, or to protect the whole head. Have at least one with you. Additionally, have a hat, either a wool watch cap or an earflap hat.
If possible, select a campsite near the top of a hill. The cold air sinks into the valleys, so it can be 5-10 degrees warmer on hilltops. Make sure that you are sheltered from any wind. If no shelter is a available you may have to construct a wall or other shelter to block the wind. I'm not going to go into the many styles and techniques for building snow shelters, but I can personally attest to how wonderful a snow cave can be. They warm up quickly to a relative balmy 32 F regardless of outside temperatures.
If you bring a tent, ensure that it will be able to withstand any winds you expect. A tent is not always necessary and I have spent many beautiful nights under the stars and northern lights.
Everyone's body reacts differently to sleeping in cold weather. Some sleep with relative ease, but others sleep "cold" and may want warmer sleeping bags. You basically have two choices for sleeping bag materials, down and synthetic. Synthetic is usually cheaper, lighter, and more compactable but it can lose its insulating value in just a few years as it becomes compacted down. I'm not discounting synthetic sleeping bags... they can be excellent for fast light travel, but don't count on one lasting forever. Down sleeping bags are heavier, but they will last longer and I believe they are more trustworthy. I am a "cold" sleeper, so I generally add 20 degrees to whatever the bag is advertised as (So -20 F rated bag becomes a 0 F bag). You won't necessarily freeze to death if your bag is not warm enough, but you will spend a miserable night with little or no sleep, which could be very dangerous after two nights of sleep deprivation. Make sure your mummy bag fits almost perfectly. The more dead space you have, the less efficient your heat retention. Maximize the bags warmth by keeping the drawstrings around your face tight. Always ensure that your breath vents out of the bag to prevent a build up of moisture.
Insulation from the ground is at least as important as insulation from the air, as lying on a cold surface will conduct large amounts of heat from your body. In the winter I use two thick foam pads for sleeping. I advise against air inflated pads because they are vulnerable to leaks that render them useless. Also, foam pads can be used as splints, makeshift sleds, etc. I have used spruce boughs in place of sleeping pads and it wasn't the most comfortable but it worked.
Wear several layers into the sack if necessary; especially dry socks to prevent trench foot. You may even want to bring a watch cap to be worn only in the sleeping bag. Items that need to be dried can be brought into the sleeping bag, but they will rob you of some heat. At night I like to fill my Nalgene water bottles with hot water and bring them into the bag. You may also need to bring battery operated devices to bed with you to preserve charge. This ensures you have some water in the morning and also keeps your feet warm.
As I learned the hard way a few years ago, compressed gas does not work in extreme cold conditions. Use a stove that is manually pressurized like the Mountain Safety Research Whisperlite. I have used this rugged, self cleaning, reliable stove when I climbed Mount McKinley (Denali) and other Alaska Range trips and it has never let me down. I recommend one stove per person as you will need to melt large quantities of snow for water. Be very careful to not get stove fuel on your skin during extreme cold. Because its freezing point is much lower than water, it could cause instant frostbite. When melting snow, make sure you start with a small amount of liquid water at the bottom; otherwise the bottom of your pan will burn rather than melting the snow.
As with any type of camping, a fire can be a welcome addition to your camp. Starting a fire in below zero temperatures will challenge your patience and skills. See Jack London's short story "To Build a Fire."
The farther north you are, the shorter your winter days, so try to have camp broken by first light. Fill your water bottles for the day with warm water and wrap them in whatever insulation you have in your baggage so that they don't freeze.
For snow travel, you will most likely need skis or snow shoes. Walking through deep, powdery snow without them will quickly exhaust you. You may feel like a crusty Sourdough when you wear your old fashioned ash and rawhide snow shoes, but I recommend modern, rigid plastic snowshoes with crampons for effective travel on hills. A sled is another tool that can make your winter travel easier. Although expensive purpose built can be had, I use a reinforced kiddie plastic toboggan. On level terrain, your sled can be your best friend, allowing you pull more than you can carry on your back. If you are going up steep hills, I recommend you keep most of the load on your back.
Keep in mind that your firearm may not function properly in sub-zero temperatures. Strip all oil from your gun in cold weather, or risk having the action locked shut. Keep in mind that firing a gun in extreme cold weather causes the weapon's temperature to rise rapidly, which could affect the temper of the steel. Usually this won't be a problem if you are just taking a few shots at some game, but if you are in a sustained gun battle with a pistol or an assault rifle, you risk severe damage to your firearm. One solution to this is to hold your weapons inside your layers to keep them warm. Of course, this presents the problem of having a giant chunk of cold metal robbing you of your heat.
Moisture is going to be enemy number one in the extreme cold. Moisture from your body will wick its way through your layers and freeze on your outer layers. Your eyebrows and beard will be covered with frost. You must constantly work to keep this frost off your clothes. Brush it off regularly. Adjust your layers so that you do not break a sweat. Sweat build up can wreak havoc in cold weather. This highlights the importance of conditioning for survival. Carrying a 70 pound pack while pulling a 45 pound sled without sweating takes a lot of exercise. Keep in mind that your nose will run in the cold air. Bring plenty of Vaseline to keep your face from becoming chapped.
As with any activity, hydration is key. The dry air will quickly rob your body of moisture. Drink lots of water, especially hot drinks to keep warm. I have known people who deliberately dehydrated themselves during storms so that they wouldn't have to leave the tent to urinate. This is foolish and dangerous. Consume plenty of food high in fat content during extreme cold. Anything with lots of butter is good. Under no circumstance consume alcohol in extreme cold. This enlarges your blood vessels and increases heat loss. Keep yourself clean to the best of your abilities. Baby wipes work well for sanitation and bird baths. I'm not going to discuss the cold related illnesses and injuries and their treatments because others have written excellent articles that cover these subjects. Suffice to say, an ounce of prevention is worth a pound of cure.
Cold weather survival, as with anything survival, is about discipline, discipline, discipline. Keep your guard up against the Wendigo, and with a little experience, you will not only survive the cold, you will thrive in it. And when the mercury rises from -40 F to 35 F, you will be looking for your Bermuda shorts and flip flops.