Crop & Pest Report


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Weather Forecast (07/25/19)

The July 24 through July 31, 2019 Weather Summary and Outlook

Temperatures averaged 3° to 6° below average in western North Dakota and 1° to 3° below average in eastern North Dakota into northwestern Minnesota during the past week (Figure 1).  The next 7 days are expected to be much warmer, with above average temperatures likely in most locations.


Most of the rain that fell in the past 7 days occurred late last week and mainly over southern North Dakota into west central Minnesota (Figure 2).  Many portions of northern North Dakota and northwestern Minnesota have recorded little if any rain in the past 10 days. 



After a brief period of below average temperatures, warmer weather is returning to the northern plains.  A trough of low pressure is expected to develop in the Pacific Northwest. This will mean a ridge of high pressure aloft will develop over our region and in turn, warmer temperatures will be pushing north. Although this pattern may break down briefly Sunday into Monday, it will likely reform next week. What this means is we may be in for an extended period with above average temperatures and below average precipitation. It is very common for there to be more evaporation than precipitation from mid-July through early September and it appears that will be the case in the next 10 or more days.  The only exceptions look to be the localized areas that may catch the core of the occasional thunderstorms that will form during this period. 

My projected growing degree days (GDDs) for the next seven days for Base 50°, 44° and 32° is presented in Figure 3. With warmer temperatures anticipated most locations are expected to receive around 10-15% more GDDs this week than what was recorded during the last seven days.


With warmer and drier conditions expected, plus less topsoil moisture available for evaporation, the number of hours with high relative humidity will be much lower in the next week for most of the area.   My projected hours with high RH through July 31 are presented in Figure 4.


Using May 5 as a planting date, accumulated growing degree days for wheat (base temperature 32°) is given in Figure 5. 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 6. You can calculate corn growing degree days based on your exact planting date(s) here:  


Using that same May 15 planting date.  The departure from last year is given in Figure 7.  Since the middle of May most locations have recorded around 200 to 250 less GDDs this year than in 2018 during the same time frame.


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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