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.

  • 2021 Degree Days - South
    Weather StationOsoyoosOliver South Oliver CentralCawstonKeremeosPenticton AirportSummerland North
    May 17, 2021210226211228237155149
    May 14, 2021184198185195204132128
    May 12, 2021173185174180189123117
    May 10, 2021164176166172182117111
    April 30, 20211101201131171258077
    April 26, 202196105991021116866
  • 2021 Degree Days - Central
    Weather StationWest KelownaKelowna SouthKelowna EastBenvoulinBelgoGlenmoreEllison
    May 17, 2021153164179174160169162
    May 14, 2021127138150151133144137
    May 12, 2021117127139141122133127
    May 10, 2021111120130133115125121
    April 30, 202178849095828985
    April 26, 202165717680707571
  • 2021 Degree Days - North
    Weather StationWinfield NorthWinfield SouthBella VistaVernon North & BXSalmon Arm
    May 17, 2021148134160161123
    May 14, 2021123111132135107
    May 12, 202111310312112499
    May 10, 20211069711411795
    April 30, 20217368798365
    April 26, 20215956667053