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Calculating degree days for non-standard bases

At our UGA cotton field day today, someone mentioned to me that they are having trouble doing degree day calculations that depend on specific bases for different crops, diseases, or insect development. You can see a list of bases for a variety of crops from the Midwestern Regional Climate Center here. But it is not always easy to find a calculator online that allows you to accumulate degree days for these bases. Here are a couple of ways you can do it.

  1. If you are in Georgia, you can use the UGA Weather Network degree day calculator at http://weather.uga.edu/?content=calculator&variable=dd&type=dt and pick the station, base temperature, and starting date you need to calculate the accumulated degree days for that base (and maximum temperature if appropriate). It gives the total number of degree days for your chosen base for the last four years, but not daily values.
  2. You can use the degree day calculator from the Midwestern Regional Climate Center at https://mrcc.purdue.edu/CLIMATE/ to do calculations for whatever station in the US is closest to your location. You will need to sign up for a free account to use this site. Make sure you pick a station that has current temperatures, since some of their sites are precip-only. On the left menu, choose Daily-Observed Data>Daily>Degree days. You can customize the base, top temperature, and starting date. It will give you daily degree days plus an accumulation for whatever your choice is.
  3. You can import the daily high and low temperature into a spreadsheet and do your own calculations.
Source: Yellow Cat, Commons Wikimedia