Heat/Comfort Index

To determine the heat index, find the outside temperature (in degrees Fahrenheit) in the left column of the heat index chart. On the top line, find the dew point (in degrees Fahrenheit). Then read down the dew point column and across the temperature row to where the two axes intersect to find the heat index. For example, if the outside temperature is 80ºF and the dew point is 65.0ºF, the heat index is 82.8. The comfort index can be roughly determined from the heat index by comparing the heat index number with the data in the summary below. Any value less than 80 is considered comfortable. Any value greater than 90 is considered extreme. Any value greater than 100 is considered hazardous. Any value greater than 110 is considered dangerous.