How warm you are, how dry you are, and how well you eat will determine whether you look back at your trip with fond memories or wake up screaming in the night from nightmares about the horror you experienced.
Staying Warm
I'll begin this section by discussing ways to stay warm throughout the entire trip. Staying warm is basically finding a way to form a shell of "dead air" around your body that your body can heat up and form a microclimate to keep you warm. So what you are looking for is a way to keep the heat your body gives off from escaping. You want it to stay close to your body in order to keep it warm. This is done by using sleeping bags and layered clothing.
While Hiking
As you hike, staying warm usually is not a problem--unless of course, it is cold and rainy. Staying dry can be a problem. You can get wet either from rain or snow or from your own perspiration. If your skin gets wet, it can lose body heat 25 times faster than if it is dry. You, therefore, want clothing that will keep you dry. This means find layers that evaporate water fast rather than just stay wet. Do not wear cotton. Cotton is great for the lower 48, but it is a killer in Alaska. When it gets wet (from rain, snow, or perspiration) it does not keep you warm. It also dries slowly. This means most t-shirts and all jeans and sweatpants are out. Find wool or polypropylene or polarfleece.
Dressing in layers gives you the opportunity to add or take off clothes as your body temperature rises or lowers. When you are hiking, you will need to keep what you wear to a minimum to keep you from perspiring too heavily. Perspiration dehydrates and can make you quite cold when you stop for a break and your body cools down. So pay attention to your body's comfort level. Since you are dressing in layers, it is very easy to add a jacket when you stop for a break. Put the jacket on before you get cold. This is the key to staying warm. Make sure you put on the extra clothing before you get cold. As you start hiking after a break and you start to warm up, drop off layers. If you are still getting too warm, open up clothing allowing air to circulate as you hike.
More on clothing for backpacking will be discussed later.
When you stop for camp, before your body cools down, add layers. In fact, add more than you think you need--it will only get cooler as the evening wears on. It is easier for your body to maintain its warmth than to try to regain it after it's lost.
Put on warm clothes before you get cold
When you stop for camp, change from your wet sweaty socks to clean dry socks.
Put on a stocking cap. Most of your body heat escapes through your head. If you can keep that heat in, it will keep all of you warm. Remember to wear the hat to bed as well.
Because muscles produce metabolic heat, keep them producing heat by exercising the big muscles such as thigh muscles and your butt muscles (jumping jacks are great)
If your hands or feet get cold, swing your arms around windmill fashion to use centrifugal force to get the blood to the extremities and bend your legs rapidly for the same effect in your feet.
While Sleeping
Use a sleeping pad to keep your body off the cold ground
Take a water bottle with hot water to bed with you.
Drink lots before bed and have a snack. This keeps your body burning calories and keeps you warm. (I know, you'll have to pee later, but it's worth it if you stay warm all night)
Sleep with your clothes for the next day in your bag (they will be easier to crawl into if they're warm in the morning)
Get a sleeping bag rated for at least 10 degrees cooler than you'll be out in and one that conforms to your body but is not too loose or too tight. Also, use a mummy style bag with a hood to keep heat from your head from escaping.
Get in your bag and do a bunch of sit-ups to warm you and the bag up
When you have to pee at night, don't put it off. It takes a lot of energy to warm up all of that water, so get rid of it.
Take an energy bar to bed for a midnight snack to keep the fire burning (except in bear country)
Staying Dry
Staying dry in Alaska is a difficult task. You are lucky if you can go backpacking for several days and not get any rain. So it is a good idea to plan on rain and prepare for it. Besides being uncomfortable when you get wet, in Alaska, there is always the possibility of hypothermia even in the summer. So staying dry is a safety factor as well as a comfort factor.
Staying dry is all in the preparation. If you prepare right, chances are you will stay dry and comfortable. Here are some tips I've learned from others and from my own mistakes:
--Never, NEVER, and again I say never trust the weather report. Always expect rain
--Pack everything in 2-gallon zip-loc bags. This way, you can organize everything in it's own bag and be able to see it.
--Make a pack cover out of a large heavy-duty garbage bag. Sure, you look like you are carrying a giant tootsie roll, but at least your gear is dry.
--Take advantage of any non-rainy weather by pinning any wet clothes to your backpack to dry as you are hiking.
--Leave the cotton (when it gets wet it sucks away body heat) and wool (it keeps you warm, but is heavy when wet and takes forever to dry) at home. Instead wear clothes that insulate when wet and dry quickly. Buy polyesters, nylon, or pile. Yes, it will cost you the big bucks to buy the right clothes, but you will never be sorry.
--Always take a few garbage bags to keep the wet clothes separate from the dry ones
--If there is a break in the weather, stop and hang things to dry. Even set up your tent if the weather looks like it might hold.
--Always wear dry clothes to bed
--Don't hang wet clothes in your tent--it will just add humidity to the inside of your tent
--Cook outside of your tent even in the rain. Chances are, you can find a spruce tree to crawl under and cook your meal and eat it in a relatively dry space.
--When it looks like it may rain for a while, find shelter such as under a spruce tree to wait out the rain, or get out your gear to prepare to yourself for the hike in the rain.
--Bring a small tarp (5x8) to use as a small awning to keep your gear under or to cook under
--If you use a down bag, KEEP IT DRY. If your down bag gets wet, it will stay that way and not keep you warm. Therefore, in Alaska, I wouldn't even consider having a down bag. I only use synthetic bags that keep you warm even when wet.
--Wear a hat with a bill to keep the rain out of your face
--Put on your rain gear and prepare for rain when it first begins, not after you are soaked.
--Pack along gaiters to keep water from running down your pants into your boots.
--Make sure your raingear is waterproof and breathable
--Make sure you have a tent that has a rain fly that has been waterproofed and seam sealed and extends to the ground. The tent should also have a "tub" style floor.
