Crop & Pest Report


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Weather Forecast (07/09/20)

The July 9 to July 16, 2020 Weather Summary and Outlook

There were many thunderstorm clusters in the region this past week.  Rainfall totals from July 2 through July 7, 2020 is presented in Figure 1.


Because of deadlines, the precipitation from Wednesday, July 8 is presented in Figure 2.  The thunderstorms Tuesday night into Wednesday morning also produced strong wind with gusts over 70 mph in some locations.


Temperatures were well above average during the past week (Figure 3).  This week will continue the trend of recording above average temperatures in most locations, but it is not expected to be as warm as it has been the last couple of weeks.


There has been much talk in social media and other sources of a heat wave projected for the Midwest.  Although that is probably true, I do not expect it to get into North Dakota.  Most of the extreme heat will remain near and south of Interstate 90.  Therefore, in southern South Dakota, southern Minnesota with the worst of the heat probably in Nebraska and Iowa. These next 7 days look a bit cooler than this past week in most locations.  Because of the higher heat will remain to our south, what will probably occur over North Dakota and northwestern Minnesota is a situation often called “ridge runners”.  Thunderstorms will form on the edge of the heat dome, which is the area served by the North Dakota Agricultural Weather Network (NDAWN) and although I expect slightly less frequency of storms, there will still be 2 or 3 waves of thunderstorms with severe weather passing through the region in the next week.  With a slightly different pattern and slightly less moisture, the number of hours in the next week with relative humidity over 85% should be lower than what was experienced recently.  Areas that do get the higher rain totals and are already wet will need to be alert for higher relative humidity levels than is shown in Figure 4.


The projected growing degree days (GDDs) base 32°, 44° and 50° for the period of July 9 through July 15, 2020 can be found in Figure 5.


Using May 1 as a planting date, accumulated growing degree days for wheat (base temperature 32°) is given in Figure 6.   You can calculate wheat growing degree days based on your exact planting date(s) here:


Using May 20 as a planting date, accumulated growing degree days for corn (base temperature 50°) is given in Figure 7.   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 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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