Growing Degree Day User Guide(SD-AWDN)

maintained by

Office of

State Climatologist


Department of Agricultural Engineering
South Dakota State University




Growing Degree Days (GDDs) are used to monitor the energy available for plant growth and development (more information). All GDD on this page are calculated by the "modified average method" with 86 F and the base temperature used for cutoff values. The source of the temperature data for the South Dakota GDD Monitor is weekly data for 66 NWS Cooperative Stations and daily data from 10 SD-AWDN stations operated by:


South Dakota Agricultural Experiment Station
College of Agriculture and Biological Sciences
South Dakota State University.


The SD-AWDN stations are interrogated daily by the Office of Climate and Weather Information, Agricultural Engineering Department

Growing Degree Days can be used to monitor and project critical stages in crop production including planting, weed and pest control, and harvest problems.

This site provides the tools to do that. Daily updates are provided at 12 South Dakota Automatic weather stations, other bordering states, and 18 South Dakota Airports.

The set of 30 station have been selected for comparing the 1998 & 1999 growing season to the normal period of 1961-90 and the crop years of 1991-1997. The Base 50 is the most common and is equivalent to the GDU used in seed corn literature.

The GDD accumulation begins on April 1, 2002 for the spring season. When computing the GDD accumlation total for a crop, it should include only those that have occured since the day of emergence. YOU will need to adjust the totals in the tables substracting the total on the day of emergence from the total on the current day.

It is good practice to record the growing degree days accumulation for the critical growth stages and other dates such as planting and emergence, crop scouting dates, pest and weed control activities along with precipitation, crop varieties, yields, and other pertinent data.

The GDD information take into consideration the variation in the dates from year to year caused by the seasonal shifts in temperature.

SD-AWDN Growing Degree Day summary of the day

SD Airports Growing Degree Day summary of the day

SD-AWDN Stations 2002 Growing Season Accumulative Totals

SD Airports 2002 Growing Season Daily Accumulative Totals

GDD Normals and 1990s data

Daily Growing Degree Day Summaries for 1998 - 2001 Growing Seasons

SD-AWDN Stations 2001 Growing Season Daily Totals

SD Airports 2001 Growing Season Daily Accumulative Totals

SD-AWDN Stations 2000 Growing Season Daily Totals

SD Airports 2000 Growing Season Daily Totals

SD-AWDN Stations 1999 Growing Season Accumulative Totals

SD Airports 1999 Growing Season Daily Totals

SD-AWDN Accumulative Totals for 1996-1998

Return to SD Climate

1996 Growing Season Daily GDD Summary

Hourly and daily weather observations for the previous day




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More on GDD from Iowa State University

More on GDD from Michigan State


Created: 12 Feb 1996 Last modified: 7 February 2003