Heat index is the temperature that it feels like to the human body and is also referred to as the feels-like temperature or the apparent temperature.
Oftentimes, it will feel much hotter than what the thermometer reads.
This is especially true on hot and humid days because the body can’t cool as efficiently. When the heat index is high, people become more susceptible to heat exhaustion or heat stroke.
Watch the video above to learn how humidity impacts how you cool down, and learn the math behind the science.