Degree Day Information
- Reflects how warm or cold it was during a specific period.
- The larger the number, the colder the temperature was.
- You usually use more heating fuel in colder weather because your furnace is working harder to maintain comfortable temperatures.
- Degree day calculations are based on the assumption that a building does not require any heat if the outside temperature averages 65 degrees during a 24-hour period.
Calculate degree days
- Add the highest temperature to the lowest temperature for the period.
- Divide the total by two.
- Subtract the result from 65.
If the day's high temperature was 30 degrees and the low was 10 degrees:
Use degree days to compare energy consumption for a given time period:
- Calculating your energy use per degree day will reduce the weather impact on your comparison.
- To find natural gas use per degree day, divide the number of therms used by the number of degree days for the same period.
Example therms for an example home:
- 137 therms for the billing period in December 2019.
- 143 therms for the billing period in December 2020.
Degree days for example billing period:
- 1,080 degree days during the December 2019 billing period.
- 1,324 degree days during the December 2020 billing period.
Natural gas use per degree day:
- .127 in December 2019.
- .108 in December 2020.
This home was using energy more efficiently in December 2020.
Find heating and cooling degree days and temperature information at:
Wisconsin State Climatology Office