The chart is a grid where you can find the heat index temperature by looking at the air temperature and relative humidity. For example, the NWS says if it's 96 outside and the humidity is 65%, the ...

The chart is a grid where you can find the heat index temperature by looking at the air temperature and relative humidity. For example, the NWS says if it's 96 outside and the humidity is 65%, the ...

What does the heat index chart look like? To get an idea of how air temperatures and humidity levels produce apparent temperatures, here is the NWS' heat index chart.