Have you ever had to deal with a scary situation while out camping or hiking?
Last month I had a friend who went camping. We haven't had a cold winter, but in January the temperatures were dropping below freezing in the evening. The day he went it rained. He was experienced, and knew to dress in layers. That evening, he had to trek to the nearest building, and by the time he got there his whole body was numb. He was developing hypothermia. He couldn't get dry, and his layers soaked through, which means he couldn't warm up. Even a week later, he was not back at 100 percent. He was fine, but it could have gotten worse. So what happened?
His bottom layer was thermals--this is smart. I highly recommend that. Thermals hug our body which traps our body heat close to us, and helps keep us warm.
His second layer was also smart--it was a thick, warm, fleece type layer that helps with keeping us warm.
His third layer was a light jacket, and that's where things went wrong. The top layer, for both pants and jacket, should be wind and waterproof. I even recommend waterproof hiking boots. Had his top layer been waterproof, his other layers never would have gotten wet, and his body never would have started freezing.
Waterproof pants are easy to find at any Dick's Sporting goods store, online, or maybe even at REI. I recommend Merrell's waterproof ankle high boots to hike in--those have saved me on hikes more times than I can count. Even on days when it's not raining, having waterproof boots have allowed me to continue on a trail where the trail takes you through the edges of a lake.
My friend is okay, but if he hadn't left the camp to go seek shelter, or had gotten lost on the way, he probably would not have been okay.
In the winter if you're camping, or even if you're hiking, I recommend at least 3 layers--the bottom being thermals, middle being fleece, and top being waterproof.