It's been VERY hot out this week with lots of really high numbers flying around trying to describe what it feels like outside. I know what the temperature means (measurement of the speed of really small particles) but wasn't really entirely sold on what the heat index represented so I decided to find out. The heat index tells you how hot it feels like taking into account the air temperature and the humidity. Humidity measures the amount of water vapor in the air so the more humid it is outside the more heat your body retains (i.e. it feels WAY hotter because your body isn't releasing the heat as well as when it is less humid). This often gives you a feeling of not being able to breathe as easily. So when the heat index is 113, you don't want to be outside or else you might just melt!