Apparent Temperature

Apparent temperature is an index designed to determine the temperature felt by the human body and varies with changes in temperature and humidity.

The Apparent Temperature is also called Heat Stress Index.

When it's hot, the human body tends to restore balance through sweating, which evaporates and cools the skin. Moisture limits the possibility of completing this process.
Therefore, in the presence of heat (i.e. heat with a high percentage of humidity), the human body has greater difficulty in cooling down and this leads to the feeling of a higher temperature that is measured with the Apparent Temperature.