The first thing to remember is that “cotton kills.” This may sound dramatic, but that’s what you often hear from hikers and outdoor people. You need to wear synthetics such as nylon or Gore-Tex if you are going to work up a sweat in rainy weather and in cold temperatures. Soaked cotton doesn’t keep you warm and contributes to dehydration. Synthetics wick up sweat and moisture and keep the body warmer.
If you wear soaked cotton, when you stop to camp those clothes will stay wet on your body. They take a long time to dry, and you will remain cold. After a long hiking day, one of the first things I do is change into dry clothes. It’s a great feeling. In the morning, I remove those dry clothes and save them for that night. If clothes from previous days aren’t completely dry, I’ll wear them anyway, just so I can always have a dry change at night to sleep in.
The pictures show my Marmot shell. I’ve said before that a rain/storm shell is my most important piece of clothing. It keeps me dry; it retards the wind and cold. Note the zipper-adjustable vents. No matter where I go, short hike or long, whether the day is sunny or warm, my shell is in my pack for when the weather changes.
The thing to be mindful of are the extremities–fingers and hands, toes and feet, head. You need to keep these areas warm and as dry as possible. I have light Gore-Tex gloves that I usually wear separately, but I can also use them as liners under heavier mittens. You can use an extra pair of socks as mittens if your handwear is lost or drenched. I always carry extra socks because wet socks and blisters go together, and I want my feet to be dry and warm. That’s a Gore-Tex baseball cap under my hood in the pictures. I’ll switch it for a knit ski hat if it gets really cold. I’ve read that there is a lot of heat loss from an uncovered head.
Keep dry, keep warm, and you are on your way to hiking safely.