Growing Degree Days, Soil Temperature, Precipitation, and Evapotranspiration Rates Reports 1988 through 2021

On March 1, 1988 temperature readings from various locations throughout Long Island were collected, which was the beginning of the reporting of Accumulated Growing Degree Days (GDD) by Cornell Cooperative Extension – Suffolk County. This was in response to GDD being used for the first time in the Pest Management Guidelines for Commercial Production and Maintenance of Trees and Shrubs or, as it was called earlier, The Cornell Recommendations for the Commercial Production and Maintenance of Trees and Shrubs. This publication used GDD as one of the tools for managing insects that attack woody trees and shrubs.

Since 1988 the weather data that has been collected has increased due to requests from various sectors of the horticultural industry located on Long Island. Accumulated GDD is being utilized by the arboricultural industry to track insect pests on woody trees and shrubs. Vineyard managers are tracking grape development using accumulated GDD. Agencies responsible for tracking the movement and developing management strategies for the Asian Longhorn Beetle are utilizing accumulated GDD from western Suffolk County, Nassau County and New York City. In 2004 soil temperatures (including soil GDD) were reported.

Eventually members of the industry started to become interested in the rate of precipitation during the growing season. Many growers of horticultural crops monitor precipitation on their farms, but precipitation does vary widely depending where you are located on Long Island. Members of the arboricultural, landscaping and irrigation industries servicing customers over a wide range of Suffolk County realized how varied precipitation rates can be from any one rain event. In a response to their needs Cornell Cooperative Extension – Suffolk County started providing daily precipitation rates. In 2006 we started providing evapotranspiration rates (ET) as well. Both precipitation and ET can be used as a guide for determining when supplemental irrigation needs to be applied to crops, landscape trees and shrubs and lawns on Long Island.

Links on the left are the final GDD, Soil Temperatures (including GDD), Precipitation and ET reports for previous years.


Sandra Vultaggio
Horticulture Consultant

Last updated December 21, 2021