The entire NDAWN (North Dakota Agricultural Weather Network) mesonet recorded above average temperatures over the past week (Figure 1). Northwestern North Dakota in particular was very warm, easiest the hottest week of the year for that part of North Dakota. Several sites had multiple 100° plus maximums with other days being mostly in the 90s. In eastern North Dakota and northwestern Minnesota temperatures were consistently in the 80s for maximums and 60s for minimums, making for above average temperatures, as well.  These next 7 days will be a mix of above and below average temperatures with the cooler days offsetting the warmer days meaning average to below average temperatures over the next week taken as a whole. Hurricane Laura may enhance the trough of low pressure building across the eastern part of the United States which in turn may bring some of the coolest air since last May for a couple of days early next week, to the Northern Plains and upper Midwest.

Rain in the past week was highly variable with most locations recording little or no rain with pockets of heavier rain associated with thunderstorms Sunday night into Monday (Figure 2).  The most likely periods for rain in the next week appear to be today (Thursday) into Thursday night, then on Sunday into Sunday Night. Both events will be associated with cold fronts moving across the Northern Plains.

Looking back at rainfall since May 1, a majority of the region has recorded drier than average rainfall during the 2020 growing season. The Red River Valley in particular has been a notable exception with most locations between 100% and 120% of normal with pockets of very wet conditions in the central and northern valley and also in northwestern Minnesota (Figure 3).

The projected growing degree days (GDDs) base 32°, 44° and 50° for the period of August 27 through September 2, 2020 can be found in Figure 4.

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: https://ndawn.ndsu.nodak.edu/wheat-growing-degree-days.html

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:  https://ndawn.ndsu.nodak.edu/corn-growing-degree-days.html.

Soybeans also use base 50° like corn, but NDAWN has a special tool for soybeans; based on planting date and cultivar it 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:  https://ndawn.ndsu.nodak.edu/soybean-growing-degree-days.html

Daryl Ritchison

Meteorologist

Director of the North Dakota Agricultural Weather Network