Crop & Pest Report


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Weather Forecast (06/25/20)

The June 25 to July 1, 2020 Weather Summary and Outlook

Much of the rain that fell this past week occurred before sunrise last Thursday, June 18 associated with the thunderstorms that dropped localized heavy rain during the evening hours on Wednesday, June 17.  Otherwise, the main precipitation event was on Saturday evening when some areas recorded 1 inch plus totals, especially in the central Red River Valley as the Finley, Mayville and Eldred NDAWN stations all recorded over 1 inch of rain. This week there will likely be thunderstorms moving through the area tonight (Thursday), then additional opportunities next week as a slight shift in the upper level wind will bring more favorable conditions for thunderstorms. That transition will also bring above average temperatures through the middle of next week.


Temperatures were below average across North Dakota and northwestern Minnesota this past week (Figure 2). Persistent cloud cover made northwestern North Dakota into northeastern Montana record temperatures 8 to 10 degrees below the current 30 year average. As already hinted to, the next 7 days look to be much warmer with above average temperatures meaning a noticable increase in growing degree days (GDDs).



The transition to warmer temperatures will be associated with the upper-level wind flow shifting to the southwest. This will bring with it many days with maximums in the 80s and even 90s with overnight minimums in the 60s to lower 70s. This type of pattern tends to gradually increase the amount of water vapor in the atmosphere as Gulf of Mexico moisture moves into the Northern Plains. The projected number of hours with relative humidity above 85% is presented in Figure 3. Localized variations in rainfall will create areas that have more hours than what is forecasted.


The projected growing degree days (GDDs) base 50°, 44° and 32° for the period of June 25 through July 1, 2020 can be found in Figure 4. With the expectation of warmer temperatures, these next 7 days will have a significant increase in heat units over what was recorded last week.


Using May 1 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 20 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:


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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