weather term
Heat Index
A single number that combines air temperature and humidity to estimate how hot it actually feels to the human body.
High humidity slows the evaporation of sweat, the body's main cooling mechanism, so the same air temperature can feel noticeably hotter on a humid day than a dry one. The heat index, sometimes called the 'feels like' temperature in warm conditions, adjusts the reported temperature upward to reflect that effect, and is the summer counterpart to wind chill.
Read the full article: What Does "Feels Like" Temperature Actually Mean?.