Old Wind Chill Chart
This formula was officially used in the United States through October, 2001.Credits to www.weatherimages.org.
Credits to The National Weather Service Winter Weather Awareness program.
The New (now current) formula for Fahrenheit temperatures:
Wind chill temperature = 35.74 + 0.6215T - 35.75V (**0.16) + 0.4275TV(**0.16)
In the formula, V is in the wind speed in statute miles per hour, and T is the temperature in degrees Fahrenheit.
Note: In the formula, ** means the following term is an exponent (i.e. 10**(0.5) means 10 to the 0.5 power, or the square root of V), - means to subtract,+ means to add. A letter next to a number means to multiply that quantity represented by the letter by the number. The standard rules of algebra apply.
Some links for more information:
USAToday's windchill pages
National Weather Service
Note: The new windchill calculation began to be used on this site starting in Nov or Dec, 2001.