During the winter months, it's not only the actual temperature that we worry about, but the wind chill temperature as well. The Wind Chill is based on the rate of heat loss from exposed skin caused by the combined effects of wind and cold. It is how cold the air feels to our skin. As the wind increases, heat is carried away from the body at an accelerated rate. The following is a chart that graphically correlates the properties of Air Temperature and Wind Speed.
Outdoor activity becomes dangerous.
Exposed flesh will freeze within half a minute.