The wind-chill temperature describes the increased loss of heat by the movement of the air. The wind-chill is relevant to humans and other animals that need to maintain a constant temperature that is higher than their surroundings.
The cooling power of the wind cannot be measured with a thermometer; it must be computed. The wind-chill temperature translates your body’s heat losses under the current temperature and wind conditions into the heat loses your body would feel if exposed to the existing air temperature and only a 3-knot (or about 3.5 mph) wind. This is not an easy conversion. The original wind-chill formula was devised by Antarctic explorer Paul Siple in 1945; however, research has revealed some flaws in Siple’s work, such as assuming that the wind at face level is equal to the wind at 33 feet above the surface. For this and other reasons, the National Weather Service updated its wind-chill temperature calculation in November 2001.
Dr. Ed Hopkins, Wisconsin’s assistant state climatologist, computed the wind-chill temperatures for all the hourly temperature and wind speed combinations available from Truax/Dane County Regional airport since January 1948. According to the new formulation, the lowest wind-chill temperature was -54.3 F at 4:00 and 5:00 am on January 20, 1985; the same day of President Reagan’s second inaugural, which was held indoors because of the cold Washington weather and because it was a Sunday. That was also the day of Super Bowl XIX, which was held in Palo Alto CA where the game time temperature was 53 F.