I've been caught off-guard in the winter while trying to camp; thinking I brought enough to stay warm, and not thinking about what cold weather does to your gear. I'm going to give you some tips to ensure that you can enjoy your winter camping experience.
Clothing is the first line of defense against the cold; you should dress in layers and have extra clothes for the trip in-case they get wet or dirty.
Layering - you always hear people tell you "to dress in layers", but what does that mean exactly? There are three layers that you should wear: Base, Mid, and Outer.
Base Layer - This would be your underwear layer. In cold weather I prefer to wear thermal underwear; one that wicks perspiration from your skin so you don't feel damp. No matter the condition or event, I like a good hiking sock that wicks moisture and keeps my feet warm. A good fitting set of polypropylene thermals is worth its weight in gold.
Mid Layer - This layer is the layer that retains your body heat. An example of this layer would be a light fleece or down jacket. I would consider the choice of mid-layer to be the most important in your outfit.
Outer Layer - This is your shell layer. If it is windy, raining, or just plain freezing cold, this is the layer that is going to protect you from the elements. Being old-school, I like a solid un-insulated Goretex type outer layer that breathes, yet keeps out the wind and rain.
Gloves - Yes, you'll want to layer with gloves too! I like a nice synthetic glove liner to keep my hands dry, and then a nice solid pair of lined gloves to insulate and keep out the water.
Hat - Some large number of heat is lost from your heat, insulate it with a beanie or other form of headwear. I like to sleep with a loose fitting beanie on my head.
*Important note on layering - The fabric you choose for your layers is EXTREMELY IMPORTANT.
If you choose the wrong type, it can be worse that not wearing it at all. For instance, cotton retains moisture when wet (like perspiration) and will not wick the moisture away from the body - causing you to lose insulative properties. In turn, this will make you feel cold and miserable.
There are a lot of other really good fabric choices out there including: polypropylene, merino wool, and other synthetics.
If you're the type that likes to sleep on the ground, you'll need a good tent. The ideal tent would be an insulated or 4 season tent. A 4 season tent is made to inhibit the cold and keep the warmth inside. As a general rule, 4 season tents are made to be smaller (than "summer" tents) so there is less air-space inside that will need to be heated. If you do not have a 4 season tent, or simply cannot afford one, all hope is not lost!
If you're going to be camping in a "regular tent", make sure that you make it as warm as possible!
Windows - Windows are great, but they let the heat out! You'll want some breathability in the tent to help slow condensation from building up, but use them judiciously.
Ground Cloth, Tarp, Footprint - Make sure it is waterproof! You don't want a wet tent footprint sitting against the bottom side of your tent; better yet, double up the layers! When car camping, I like to take a huge tarp, and fold it up prior to placing it under the tent... this will act as a waterproof barrier and add some insulation.
Inside Tent Insulation - Some people won't agree with me on this, but I like to have a nice, heavy blanket to cover the floor of a tent; this acts as another barrier from the heat-robbing ground, adds insulation, and feels good on your feet.
Other Warming Devices - Proceed with caution on this one! I am a cold weather weenie; I do not like being cold and am partial to heating devices like the Mr. Buddy heater or a diesel heater. Both of these will keep the inside of your tent toasty warm all night long, but they have one potentially fatal draw-back: Carbon Monoxide emissions. To combat this, I usually keep the tent windows open father that I normally would and keep a fire extinguisher and a CO monitor inside of the tent.
Sleeping Bag Selection
The sleeping bag is going to keep you warm all night long, so be sure to wear the appropriate base layer (and possibly mid-layer) when heading to bed. There are unscrupulous sleeping bag manufacturers out there that will confuse you about the temperature-rating of their bag; do some research and buy one from a reputable store that knows what you're looking for... a $25 bag will ensure that you have a sleepless night!
There are 3 main temperature ratings for sleeping bags: Comfort, Lower Limit, and Survivability. There is also a lab-certified temperature rating (displayed as "EN" and "ISO" ratings) that will help you make a more informed choice. IMHO, I get a bag that is rated for way more than I anticipate as you can always un-zip it if you get too hot. I like a nice snug mummy-style bag so there is no "extra" air-space in between me and the bag.
Pro-Tip - Sleep with your next day's clothes in your sleeping bag, that way you'll wake up with a warm set of fresh clothes to put on.
Sleeping pads are more than just a cushion underneath you, they act as insulation too. Sleeping pads are rated with "R-values" to determine how insulating they are; the higher the R-value, the warmer they'll keep you. Use closed cell foam pads too as they will insulate better than open0celled variants. In my current set-up, I place my 5 R-value sleeping pad inside of my sleeping bag and sleep inside of a sleeping bag liner.
In snow conditions, you DO NOT want to have your tent directly under trees or any other over-hanging features. Packed snow that has built up on the limbs or over-hang will eventually fall and you do not want to be underneath it when it does.
Pack it down - To make your tent floor feel less lumpy and to help insulate better, pack the snow down under your tent prior to setting it up.
Stay on a flat surface, up-hill - Camping on a flat surface will stop you from sliding around while trying to sleep; always camp on flat ground. Never set your tent up too close to a water source or in a valley, the cold air forms troughs and travels around those features. Also, don't camp on the top of a featureless hill; the wind will be howling over these areas.
Also, be sure to check whether avalanches or mud-slides can happen in your area prior to setting up camp.
Pro-Tip - Place your tent where the first light of day will hit it; you'll be happy to wake up and feel the warmth of the sun on your face.
Water Freezes! I have fallen victim to waking up in the morning, grabbing my coffee grounds and french-press only to find out my 6 gallon Scepter water can is a frozen block of ice! To help combat this, you can turn your can upside down at night (water freezes from the top-down), keep your water with you in the tent, leave it in the car, or at least leave it out where the morning sun will hit it. Double-walled water bottles will help to prevent freezing too!
Other note-worthy suggestions
Food - Calories are your friend when winter camping. You may not feel like you've done a lot of activity, but your body is burning calories extra fast keeping you warm. Make sure to eat and eat often. I like to eat shortly before bed with enough time to go to the bathroom (so you don't have to make that freezing cold journey in the middle of the night). Warm food tastes better and warms you internally as well.
Fire - Fire is the best part of camping IMO. Be sure to have multiple sources of making fire as wet wood and frozen butane lighters will certainly be an issue. I like to keep at least one butane lighter on me so that it will work when needed.
Propane - Propane is another gas that does not like the cold. Lines freeze and will make lighting up your stove or heater near impossible. I like to store the propane out of the elements and insulate the hoses.
Hand Warmers - Another trick for using handwarmers is to place them everywhere: in your coat pockets, in your sleeping bag, in your boots... everywhere! At $1 per pair, they're inexpensive and awesome! They make rechargeable battery-powered versions too!
Lotion, Vaseline, Skin Protectant - I get cracked and dry hands every single time that I camp in the cold. Make sure that you keep your skin hydrated and protected to help prevent cracking!
What suggestions or comments do you have to add? Let me know!