Hypothermia is a sudden drop in body temperature that can kill you. If you dress properly and exercise vigorously enough, it should never happen to you. Your body sends you signals as your temperature starts to drop. With a one degree drop in temperature, your speech becomes slurred. This, in itself, is not dangerous, and occurs when people stay out in temperatures below 35 degrees, but it serves as a warning that you are losing more heat than your body is producing. To protect yourself, you can produce more heat by exercising harder or you can conserve heat by adding more layers of clothes.

With a drop of three degrees, you'll find it difficult to coordinate your fingers. Seek shelter immediately. When your temperature drops five degrees, you won't be able to walk and you'll stumble and fall and not be able to get up. Then you may not be able to get out of the cold and your body temperature can continue to drop rapidly and you can die. If your clothes are wet, your temperature will drop even faster. Take the warning signals seriously; if you have slurred speech or difficulty using your hands, take action or you may not get another chance.

Frostbite means that your skin is frozen. You have plenty of warning before that happens. Your normal skin temperature is around 90 degrees. As your skin temperature starts to drop, blood vessels close and your skin turns white. When the temperature reaches 59 degrees, your body attempts to rewarm your skin by opening the blood vessels, causing your skin to tingle, itch, burn and turn red. When this happens, get out of the cold. If you don't, the blood vessels in your skin will close down again and your skin temperature can drop below 30 degrees and start to freeze.