• Heating Degree Day (HDD) measures the average number of days the temperature falls below 65 degrees Fahrenheit. At this temperature, heating systems are turned on in buildings to maintain an average temperature of 70 degrees.

  • The hard drive is set to zero if it has a negative value.
  • HDD is used in the settlement of weather futures contracts, which are used as a risk management tool in weather-affected industries such as construction and agriculture.