Crop & Pest Report


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Weather Forecast (07/18/19)

The July 18 through July 14, 2019 Weather Summary and Outlook

The rain this past week was much more hit and miss than what was recorded the week before (Figure 1).  There were definitely exceptions, Mott for example, but much of the region recorded below average rainfall through Tuesday.  There was a narrow band of rain that occurred Wednesday morning from northern Steele County into Clay County, Minnesota.  Those totals can be found in Figure 2.



After a couple of weeks with near average temperatures, this past week was well above average with the exception of near the North Dakota/Montana border (Figure 3).   The rain from Wednesday into Wednesday night (the past 24-36 hours) was associated with a cool front that will bring in noticeably cooler air, especially on Saturday, Sunday and Monday to the northern plains.  Much of the lower 48 states will be experiencing well above average temperatures for the next few days, but our region will be the exception. 


In the short term, a ridge of high pressure aloft will build over the Rocky Mountains.  That will transition the upper level wind flow to come in from the northwest bringing in that cooler air this weekend into early next week.  That transition will also break the heat wave that is and will be occurring across much of the eastern one-half of the United States during the next several days.  Next week will be significantly cooler from the Rocky Mountains eastward.  Because North Dakota and northwestern Minnesota will be experiencing the cooler air first, as the eastern part of the United States cools down, our region in turn will slowly warm up.  Much of that warm up will occur toward the end of next week, meaning, that much of the next seven days will record below average temperatures.

My projected growing degree days (GDDs) for the next seven days for Base 32°, 44° and 50° is presented in Figure 4.   With cooler temperatures anticipated most locations are expected to receive 10% to 20% fewer GDDs this week than what was recorded during the last seven days.


The recent rains, plus the transition to cooler drier air from Canada taking a couple of days to arrive, the number of hours with relative humidity (RH) above 85% will still be quite high through the weekend.  Fewer high humidity periods are expected early to the middle of next week.  My projected hours with high RH through July 24 is presented in Figure 5.


Using May 5 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 15 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 the 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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