Just fyi...from the NOAA website, their definition of wind chill...
1. What is Wind Chill Temperature?
The wind chill temperature is the temperature that it feels like outside to people and animals. Wind chill is based on the rate of heat loss from exposed skin caused by combined effects of wind and cold. As the wind increases, heat is carried away from the body at an accelerated rate, driving down both the skin temperature and eventually the internal body temperature. Therefore, the wind makes it feel much colder. If the temperature is 0 degrees Fahrenheit and the wind is blowing at 15 mph, the wind chill is -19 degrees Fahrenheit. At this wind chill temperature, exposed skin can freeze in 30 minutes.
Estimated time to frostbite from exposure due to unprotected skin, seems to be the main reason for the existence of the wind chill factor.