WCT Index Calculations

Index DetailsWind Chill Temperature Comparison

Specifically, the new WCT index will:

  • Use calculated wind speed at an average height of five feet (typical height of an adult human face) based on readings from the national standard height of 33 feet (typical height of an anemometer)
  • Be based on a human face model
  • Incorporate modern heat transfer theory (heat loss from the body to its surroundings, during cold and windy days)
  • Lower the calm wind threshold to 3 mph
  • Use a consistent standard for skin tissue resistance
  • Assume no impact from the sun (clear night sky)


The new formula was incorporated into the latest software build installed on the NWS Advanced Weather Interactive Processing System (AWIPS) on November 1, 2001

In 2002, adjustments for solar radiation (impact of the sun) for a variety of sky conditions (sunny, partly sunny, and cloudy) may be added to the calculation model.