Wind Chill Temperature (Latest Equation Effective November 1, 2001)

Wind Chill: A measure of the rate of heat loss from a human body, taking into account both the temperature and the wind speed at an average height of five feet.

In other words, the faster the wind blows in an atmosphere of cold dry air, the faster moisture evaporates from the skin. Since evaporation is a cooling process, the body cools faster when exposed to windy, dry air. A new equation for determining the wind chill temperature was developed in 2000 by meteorologists from both the United States National Weather Service and the Meteorological Services of Canada.

This new wind chill temperature equation uses recent advances in science, technology, and computer modeling, to provide a more accurate and understandable measure of the effects of wind and cold on the human body. The new wind chill equation replaces the original equation which was developed in 1945 and will serve to standardize the measure throughout North America. The equation is valid on a clear night only which means in its current form does not take into consideration solar heating during daylight hours which would have an impact on reducing the effect of the wind on heat loss from a body. It should also be noted that the cooling effect of the wind only has an impact on living things. There is no wind chill effect on inanimate objects.

Wind Chill = 35.74 + 0.6215T - 35.75(V0.16) + 0.4275T(V0.16)

Where T = Air Temperature in Fahrenheit and V = Wind Speed in miles per hour

The equation yields a temperature in degrees Fahrenheit

The chart below is a graphical representation of the wind chill temperature. Frost bite, on average, can occur on exposed skin surfaces within fifteen to thirty minutes when the wind chill temperature reaches the values highlighted in blue. When the wind chill values highlighted in red are reached, frost bite on exposed skin surfaces, on average, can occur within five minutes

Click on the wind chart to view larger font size.