Definitions for "Degree-Day"
A unit that represents one degree of deviation from a reference point in the mean daily outdoor temperature (usually 65°F) and that is used to measure heating and cooling requirements.
A unit of heat. The equivalent of one degree of temperature, maintained for 24 hours, above or below any specified base temperature, e.g., 2° for 12 hours or 0.5° for 48 hours. Often used in predicting the time of incidence of insect pests in the spring. For purposes of plant growth and animal development, the base temperature may be the temperature above which growth can be initiated and maintained.
One degree of temperature above an insect's developmental threshold, lasting for one day. It is the most common method of expressing heat units.