Crop & Pest Report


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Weather Forecast (07/26/18)

The July 26 through August 1, 2018 Weather Summary and Outlook

The past seven days was the first week with widespread below average temperatures being recorded at North Dakota Agricultural Weather Network (NDAWN) stations, in over two months (Figure 1). There will be a warm up for a few days next week, but the cool air expected through the weekend will probably be enough to keep the temperatures at or below average for this forecast period.


All NDAWN station recorded at least some rain during the past seven days (Figure 2). The heaviest rain occurred in southeastern North Dakota into west central Minnesota, rain that was associated with a slow moving upper-level low pressure system last Thursday.


The cooler weather in place this week will last through the weekend. Precipitation looks to be widely scattered during this forecast period with Friday night into Saturday looking to be the time frame with the most widespread precipitation. The odds are that many locations will record little or no precipitation through the middle of next week. The main change in this period will be the trend toward much warmer temperatures next week, especially Tuesday and Wednesday. It will feel like summer for a few days, but beyond that, another period of cooler weather is expected as we move into August. My projected growing degree days (GDDS) base 32°, 44° and 50° for the period of July 26 through August 1 is presented in Figure 3.


The projected number of hours with relative humidity (RH) at five feet above the surface is presented in Figure 4. There will be more hours with high RH today through the weekend then there will be next week, but with the increase in temperatures expected after the weekend, the risk of disease would be higher after the weekend than before.


Using May 5 as a planting date, the accumulated wheat growing degree days (Based 32°) through July 24, 2018 is presented in Figure 5. You can find your exact GDDs for your planting date(s) at:


Using May 10 as a planting date, the corn accumulated growing degree days (Base 50°) through July 24, 2018 is presented in Figure 6. You can find your exact GDDs for your planting date(s) at:



Daryl Ritchison


Interim 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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