Ag Weather Forum

Cool Week to Limit Growing Degree Day Numbers

Bryce Anderson
By  Bryce Anderson , Ag Meteorologist Emeritus
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Seven-day forecast temperature trends through Sunday, June 16, maintain a near- to below-normal trend over the primary U.S. crop areas. (DTN graphic)

The extent of delayed planting of the 2019 U.S. corn crop appears to be coalescing around the idea that, in general, the U.S. corn crop is around three weeks late. With that in mind, the temperature trend takes on extra urgency for the crop. In central Illinois, for example, a lag of three weeks puts crop maturity into late September for the earliest occurrence, as opposed to early September. That's enough of a delay to put corn maturity into a time frame when there is a 20% to 30% probability of overnight low temperatures hitting the freezing mark of 32 degrees Fahrenheit.

And, at this point, temperatures are not cooperating on the side of growing degree day accumulation. Most of this June 10-14 week has average temperatures across the central U.S. forecast at from 4 to 12 degrees Fahrenheit below normal, with the coldest departures over the Great Lakes. And, from forecast model indications, this cool pattern stays in effect through Monday, June 24 -- almost the entire remainder of the month of June.

There is still time for crops to receive performance-enhancing heat. Much of the 2019 corn crop will be pollinating in mid to late July. But growing degree day count will be a big detail the rest of this season. After all, a lot of the prime time has, literally, floated away.

Bryce Anderson
Twitter @BAndersonDTN



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