Heating Degree Days

Heating degree day (HDD) is an index designed to reflect the energy demand for heating. It is defined as the number of degrees that a day's average temperature is below 65°F (18°C). For example, if the day's average temperature is 50°F, its HDD value is 15. If the temperature is above 65°F, the HDD value is zero. Heating degree days can be accumulated over periods of time to provide an estimate of seasonal heating requirements.

The HDD forecasts are issued for major cities in the U.S., Canada and Europe, which are traded on the Chicago Mercantile Exchange (CME). These forecasts are first available for paid subscribers only. All other subscribers can have access to those forecasts after the start of the calendar season, i.e., December 1st.

Since our temperature forecasts are currently prepared primarily for the calendar winter season (December-February), the HDD forecasts are issued for the same season. Occasionally, however, we also issue HDD forecasts for individual months within the heating season, November through March. These "forecasts by opportunity" are available for paid subscribers only.

The skill scores presented here are for mean seasonal HDD forecasts. The observed values are settlement data reported by the CME. Click here to see how skill scores are calculated.