This winter, the National
Weather Service and Meteorological Services of Canada will use the following Wind
Chill Temperature Index, designed to calculate a more accurate reading of how
the cold air feels on the human skin.
Since 1945, the United States and Canada have used an index, which relied on observed winds 33 feet above the ground, and focused on how fast the cold temperatures combined with winds made water freeze. The new index accounts for the wind effects at face level, and a better calculation for body heat loss. For example, under the old index system, a temperature of 20 degrees, with a 15 mph wind, translated into a reading of five degrees below zero. The new index calculation would translate the same conditions to six degrees above zero.
The new index is based on:
NWS Office of Climate, Water and Weather Services, which includes the chart and wind chill calculator that appear above.