In the fall of 2000, the Office of the Federal Coordinator for Meteorological Services and Supporting Research (OFCM) formed the Joint Action Group for temperature indices (JAG/TI) to upgrade and standardize the indicies for temperature extremes. This followed conclusive evidence that the then existing wind chill temperature chart was seriously flawed. After reviewing scientific publications of alternative approaches, the JAG/TI selected the undersigned authors to develop a new wind chill temperature (WCT) chart. The chart, based on modern heat transfer theory utilizing a model of the adult face, was implemented by the weather services of the U.S. and Canada in November, 2001. This paper describes the basis for this new chart and the results of human trials that were utilized to support this project.

This paper will discuss the flaws in the original WCT chart, depict the model utilized for the new chart, provide the heat transfer theory employed, and describe the human trials utilized to provide the necessary thermal characteristics. The final equations in both English and metric units will be provided as well as the rationale for including frostbite risk warnings in the new chart.