(Meteoroloji) Wind chill (often popularly called the wind chill factor) is the felt air temperature on exposed skin due to wind. The wind chill temperature is never higher than the air temperature, and the windchill is undefined at the higher temps (above 10 °C [50 °F]). Humidity on the skin can result in a higher felt air temperature, which is accurately termed the heat index (or humidex), and is used instead