What Is Wind Chill, And How Does It Affect The Human Body?
In Chicago, for example, wind gusts of up to 24 miles per hours will generate a temperature with wind chill of minus 50 or 60 degrees Fahrenheit. The wind chill index was adopted by NWS in the 1970s and then updated in 2001 to reflect modern understandings of human body temperature. The temperature of the air is the same on both days, but gusts of wind strip heat away from the body, making a person physically colder than they would be on a less windy day.
Source: www.smithsonianmag.com