Temperature variations can affect energy usage. Degree days measure the demand for heating and cooling. A degree day is the difference between 65 degrees Fahrenheit and the average of the high and low temperatures in a given day.
The difference above 65 degrees Fahrenheit is a Cooling Degree Day. The difference below 65 degrees Fahrenheit is a Heating Degree Day. The higher the number, the more energy will be used for heating and cooling.
There is a direct correlation between temperature variations and degree days and monthly utility billing amounts.