While the thermostat may say it's 32 degrees outside, your body may feel like it's 15 degrees colder. This sensation is measured in wind chill temperatures, which are based on the rate of heat loss from exposed skin caused by wind and cold. As the wind increases, it draws heat from the body, driving down skin temperature and eventually the internal body temperature. The National Weather Service implemented a new wind chill index in 2002 that is designed to more accurately calculate wind chill. Air Temperature (°F) = Wind Speed (MPH) = Old Wind Chill Index New Wind Chill Index Courtesy National Weather Service Note: The previous index underestimated the time to freezing and overestimated the chilling effect of the wind. The new index is based on heat loss from exposed skin and was tested on human subjects. It also has a frostbite indicator, showing the points where temperature, wind speed and exposure time will produce frostbite on humans. Wind Chill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph.
Note: The previous index underestimated the time to freezing and overestimated the chilling effect of the wind. The new index is based on heat loss from exposed skin and was tested on human subjects. It also has a frostbite indicator, showing the points where temperature, wind speed and exposure time will produce frostbite on humans. Wind Chill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph.