Degree days is a term used to measure how cold or hot the weather is by tracking the difference between the average temperature and a desired temperature. It helps estimate the amount of energy needed to heat or cool a building. Full definition
For example, this week has 40 degree and 70 degree days in the forecast. (everydaychiffon.com)
Its forecast has 2 percent fewer heating degree days (warmer) this winter than the 1980 - 2010 average. (truebluenaturalgas.org)
The warm winter months during 2012 (particularly in the first quarter) more than offset a slight increase in cooling degree days during the summer months. (eia.gov)