Early symptoms include shivering, cold and pale skin, apathy, and impaired judgment. Later symptoms include drowsiness or weakness, confusion, slow pulse and breathing, and passing out. Hypothermia is an emergency. It may result in death. Cold temperatures, dampness, and wind increase the risk of hypothermia for runners.
Sweat cools the body quickly during cold weather running.
Wind evaporates sweat even faster and the body temperature may drop rapidly. The outer layer should protect the runner from wind, rain, or snow. Wear fabrics that insulate and wick moisture away. Fabrics made of wool and polypropylene are good. Avoid wearing cotton because it retains moisture.