The formula for calculating wind chill temperature is only applicable under certain conditions, such as an atmospheric temperature less than 50 degrees Fahrenheit and a wind velocitygreater than 3 mph. Wind chill is computed using the formula WC= 35.74 + 0.621 - 35.75(V0.16) + 0.4275T(V0.16), where "V" denotes wind speed, "T" indicates air temperature and "WC" represents wind chill in degrees Fahrenheit.
The Siple and Passel Index was formerly used to compute wind chill temperature from 1945 to 2001. A new formula was then established by the National Weather Service called the Wind Chill Temperature Index. Places that are directly exposed to intense sunlight may have a wind chill temperature that is 10 to 18 degrees higher than the actual value.