Degree Days

What are degree days?

Growing degree days (DD) are a weather-based indicator for assessing crop and pest development. It is a calculation used by crop producers that measures heat accumulation used to predict plant and pest development rates. Growing degrees are defined as the mean daily temperature (average of daily maximum and minimum temperatures) above a certain threshold base temperature accumulated on a daily basis over a period of time. Daily growing degree day values are added together from the beginning of the season. Degree day totals are also used for comparing the progress of a growing season to the long-term average.

Degree Day Development Table

The codling moth, like all insects, is cold blooded. Meaning, the temperature around it determines how fast it grows and how active it is as an adult moth. We can take advantage of this to predict what life stage the majority of the codling moths population are in. Scientists have developed a model that uses degreedays to predict codling moth development. These predictions are summarized in this table.

Degree day total
(+/- 3-5 DD)
Codling moth stage of development
100Emergence of 1st brood moths from overwintering larvae
150Beginning of 1st brood egg laying
220Start of 1st egg hatch (first brood larvae)
500End of emergence of 1st brood moths
575Start of emergence of 2nd brood moths
650End of 1st brood egg hatch
700Start of 2nd brood egg hatch (2nd brood larvae)
1140End of 2nd brood moth emergence
1160Start of 3rd brood moth emergence
1275End of 2nd brood egg hatch
1300Start of 3rd brood egg hatch

A complete codling moth degree day development table is also available as a PDF – Full Codling Moth Degree Day Development Table.

More information about the codling moth stages of development, see Codling Moth.

Degree Day Tables

The degree day totals in the table below indicate the predicted stage of development of codling moth populations near specific weather stations located around the valley. Growers and advisors can use the values to determine the life stages of the codling moth in their area. This will help determine the proper time to apply ovicidal and larvicidal products to control each of the codling moth generations if needed.

  • 2018 Degree Days - South
    Weather Station Location
    OsoyoosOliver SouthOliver CentralCawstonKeremeosPenticton AirportSummerland North
    April 4, 2018172017161776
    Data from Osoyoos, Penticton and Summerland comes from Environment Canada.
    Data from Oliver south, Oliver north, Cawston, and Keremeos comes from Growers Supply's weather network.
  • 2018 Degree Days - Central
    Weather Station Location
    West KelownaKelowna SouthKelowna EastBenvoulinBelgoGlenmoreEllison
    April 4, 20188589455
    Data from Westbank, Kelowna South, Kelowna East, Belgo, Glenmore and Ellison comes from Growers Supply's weather network.
  • 2018 Degree Days - North
    Weather Station
    Winfield NorthWinfield SouthBella VistaVernon North & BX Salmon Arm
    April 4, 201842431
    Data from Salmon Arm comes from Environment Canada.
    Data from Oyama, Winfield South, OK Landing & Bella Vista, and Vernon North & BX comes from Growers Supply's weather network.