The Wind chill measures the effect of wind speed on the perception of temperature. In windy conditions, the air feels cooler than it actually is, because of increased perspiration.

Apparent temperature is the general term for the perceived outdoor temperature, caused by the combined effects of air temperature, relative humidity and wind speed.

The Heat index measures the effect of humidity on the perception of temperature. In humid conditions, the air feels hotter than it actually is, because of the reduction of perspiration.