The growing season is going to come to an end over the course of the next three days for much of the northern Plains and for a significant part of the Midwest.
Freeze watches and warnings have already been posted for tomorrow morning in central/western North Dakota and northwestern parts of South Dakota, areas where temperatures will have no trouble getting below 32 degrees tomorrow morning (in fact I think that sub-32 degree temperatures will be seen even further east and southeast from where those advisories have been posted, possibly getting into the extreme northwestern Corn Belt).
Sunday morning still looks to be the coldest, with about anyone in the Corn Belt getting below 40 degrees for their low that morning. The eastern Dakotas, far northeastern Nebraska, northern Iowa, northwestern Illinois, and much of Wisconsin and Minnesota will get below 32 and plenty of locations will see lows dipping below 30. Record lows are likely to fall in some areas with that cold. The eastern half of the Corn Belt will be in the 30s for lows again on Monday morning and there will probably be localized places that get to 32 or a little lower.
As I have noted in the past, it is very common for hot July and/or summer temperatures to be followed by a September frost/freeze in a significant part of the Corn Belt. We saw it last year, as well as in 1995, 1983, and 1974. We even saw it in 1934, which is the year that I feel best matches the weather conditions that we have had so far this year in the Corn Belt and other parts of the Nation.
Such freezes in hot/dry years are normally forgotten though, as the heat and dryness in the summer typically pushes the crops so quickly towards maturity that a September freeze means nothing to final production. That looks to be the case this year as well, and in fact many farmers have told me they are "hoping" for this freeze to occur to given them better conditions for harvesting.
Longer term the story for late next week continues to be enhanced chances for much-needed rainfall for the hard-red winter wheat belt, with the models today quite consistent on that outlook. The forecast change today is that it looks like better odds for some of that moisture to eventually work into the Corn Belt for about month-end.
