Annual Normal Heating Degree Days (base 65° F)

Annual Normal Heating Degree Days (base 65° F)— A gross measure on average over a year (for the last thirty years) of the amount that there is a difference from 65 degrees in the direction requiring heating (Inverse Index.) Degree days represent the amount of energy needed to maintain a comfortable indoor temperature level. This measure represents the mean temperature (maximum minus minimum.) Each degree that a day's average temperature is below 65° F represents one (1) heating degree day.