Apparent temperature is the general term for the perceived temperature, caused by the combined effects of air temperature, relative humidity and wind speed. The term is most commonly applied to perceived outdoor temperatures, but of course also applies to indoors, especially to saunas or when homes or workplaces are not sufficiently heated or cooled or insulated to provide comfortable or healthy conditions.
- The heat index and humidex measure the effect of humidity on the perception of temperature. In humid conditions, the air feels much hotter, because of the reduction in evaporation of perspiration.
- The wind chill factor measures the effect of wind speed on cooling of the human body below 50 °F (10 degrees C). As airflow increases over the skin, more heat will be removed. Standard models and conditions are used.
- The wet-bulb globe temperature (WBGT) combines the effects of radiation, humidity, temperature and wind speed on the perception of temperature. It is not often used as the resulting figure is very location specific (e.g.: cloud cover and/or wind shielding).