What do windchill and heat index temperatures mean?

Windchill is a measure of how cold it feels when exposed to cold temperatures and wind. The windchill temperature is also a measure of how quickly someone may get frostbite.

Windchill chart from National Weather Service (http://www.nws.noaa.gov/om/windchill/)

Heat Index, on the other hand, uses air temperature and humidity to determine the temperature the body feels on very hot days. The Heat Index temperature assumes shady conditions. Exposure to direct sunlight can increase temperatures by up to 15°F! On a very humid day, the Heat Index is much higher than the air temperature.



National Weather Service Windchill page

National Weather Service Heat Index page