Wind chill is the air temperature on exposed skin. It is derived from the consideration of both air temperature and wind speed. The National Weather Service Wind Chill chart is presented below. Color-coding within the chart relates the Wind Chill temperature to the number of minutes before frostbite commences at that temperature:
Heat Index
The Heat Index expresses the level of discomfort, and at certain temperatures the danger, created by the relative humidity at given temperatures. Color coding in the Heat Index chart presented below express the relative danger associated with increasing Heat Index values. SpotCast Extreme returns the Heat Index value appropriate for the relative humidity at each time and location in your forecast:
