Wear the right clothing:
- Do not wear anything cotton. When you work up a sweat, your cotton gets wet and stays wet. This is a recipe for a shivery night.
- Bring one more layer than you think you'd need. It is cold on the ground, plus your body doesn't generate as much heat as when you're standing up.
- For your core body: Wear a non-cotton base layer, a light fleece sweater, and one of those thick college hoodies with a single large pocket that has two hand openings. The hoodie is the perfect outer layer because it forms a light wind shell, keeps your heard warm while you are sleeping, and provides an instant hand warmer (not all sleeping bags have that nice little feature, so it's kinda cool making your ghetto adaptation). Oh, and you can stash a water-proof glove (cycling gloves also works) in the pocket, in case your hands still get cold.
- For your legs, get fleece, thermal wear or cycling tights, all of which are warmer than silk pants. Cycling tights are a bit more wind resistant. Put rain or snow pants over the base layer to deflect the wind. You could also just wear a wind-breaking sweat pants with fleece lining, if you don't have fancy rain/snow pants.
- Bring a pair of really warm sleeping socks. If you don't hike with these, you can just bring one pair for sleeping. It's worth the weight when things get really cold, and your body starts retracting heat from your extremities to keep your core warm.
- Bring a windproof beanie that goes over your ears. Then put your hood over your head to keep it from sliding out when you sleep.
- Hydrate well, but stop drinking right before bed. The cold weather will make you want to go to the potty more often than usual. Each time you leave your sleeping bag, you'll need to warm it up all over again.
- If you have to go answer nature's call, sprint back to your tent. This generates a little bit of extra heat right before you stash yourself into the now-cold sleeping bag.
- If you are still cold, do sit ups inside your bag. You'll heat up fast, and if your bag will keep the warmth in, long after you'd stop.
Other things to make you comfortable:
- Use an insulated 4-season air mattress (Thermarest, for example). Not only does it provide cushioning, but it keeps the ground from chilling you.
- Invest in a bag liner. Silk, flannel, and some synthetics can add 5° or more of warmth and they keep your sleeping bag cleaner and might, for some people, feel better than the sleeping-bag fabric. Silk is the lightest and most expensive option.
- Bring a compressible camp pillow, which has an incredible weight-to-comfort ratio (backpacking is a trade off between light weight and comfort). Yes, you could use your clothes as a pillow, but if you're wearing all your clothes because it's so darn cold, you'll need a pillow! The generic one from REI is cheap and comfy!
Things you can ditch:
- Since you are bringing more layers than you normally do, you have to look for places to lighten the load. Double up on the food/drink pack. Consider packing single-serve soy milk instead of just plain water. It quenches thirst and it's calorie rich (compared to water).
- You probably drink less water in cold weather than in warm weather. Adjust accordingly. Don't be too stingy though. It's always better to carry more water than you think you'd need than being parched, head-achey, and grumpy, You can always spill out water.
- Outdoor activities can get so expensive, so it's best to repurpose what you already have. For example, winter cycling clothing, which are designed to wick sweat out and dry rapidly, can be repurposed for other cold activities, like hiking and skiing. They are designed to keep you warm and dry without restricting movement.
- Cycling tights take little space yet are great for keeping you warm without overheating you. However, they are designed for the a seated, not upright position, and they can get clammy if you are one of the sweaty types. Test it out first to make sure that you're comfortable with it. The generous padding that's great in cycling might get annoying in hiking.
