This formula is based upon the National Weather Service's updated Windchill Temperature Index. Temperature is adjusted for the effects of windspeed on apparent temperature as wind results in an apparent temperature that is colder than that measured by a thermometer.

Formula:

T = Air temperature in °F

V = Wind speed in mph

Wind Chill (°F) = 35.74 + (0.6215 * T) - (35.75*V^0.16 ) + (0.4275 * T * V^0.16)

Reference:

http://www.weather.gov/os/windchill/index.shtml