Crop & Pest Report


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Weather Forecast (05/20/21)

The May 20 to May 26, 2021 Weather Summary and Outlook

Last week in my Crop and Pest Report I mentioned we would likely record a warm week with spotty precipitation.  Looking at Figure 1, the spotty precipitation ended up being an appropriate term.  There were clearly pockets with some good rains, yet most of the region recorded little or no rain during the past week. 

Almost the entire North Dakota Agricultural Weather Network (NDAWN) recorded above average temperatures in the period from May 12 through May 18.  Some parts of the northern Red River Valley were 8 to 10 degrees above average (Figure 2).  This next week will probably be a bit cooler, especially across northern North Dakota, but those cooler temperatures will be associated with cloud cover and rainfall, which will be very welcomed. Most of you have likely heard that there are rain possibilities today (Thursday) through early next week.  This is the system I hinted to last week in this report.  I doubt any given spot will record precipitation each day, but there will be rain impacting at least a portion of North Dakota on each day through Monday.  There will likely be winners and losers as rain doesn’t fall evenly and there will very likely be locations that won’t get as much as they would like.  Yet, having said that, this looks to be the most widespread rain in a very long time.  Plus, the rains will come over several days, so if you don’t get much today, there will be other opportunities.  After this stretch of rain chances, I would not be surprised if another system impacts us toward the end of next week as this temporary pattern change looks to be lasting for 7 to 10 days.

wthr.1 2

The projected growing degree days (GDDs) base 50°, 44° and 32° for the period of May 20 through May 26, 2021 can be found in Figure 3.

wthr.3 4

Using May 10 as a planting date, accumulated growing degree days for corn (base temperature 50°) is given in Figure 5.   You can calculate corn growing degree days based on your exact planting date(s) here:


Soybeans also use base 50° like corn, but NDAWN has a special tool for soybeans that, based on your planting date and cultivar, it can estimate maturity dates based on average temperatures, as well as give you GDDs based on your planting date(s) you set.  That tool can be found here:


Daryl Ritchison


Director of the North Dakota Agricultural Weather Network

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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