Don’t look now, but the polar vortex is coming back. And, yes, we’re talking about the middle of the summer.

It won’t be bitterly cold as in January, when a large sub-zero Artic air mass held much of the eastern United States in its grip for weeks. Still, this polar invasion will bring temperatures to the Corn Belt cool enough for sweaters and, in a few locations, maybe heavy jackets.

Temperatures are expected to be 10-30 degrees below normal by the middle of next week before turning warmer by the weekend. Overnight lows could dip into the 40s in parts of Michigan, Minnesota and Wisconsin.

And Canada? Daytime highs in Ontario could fall into the teens.

Brrrr!

Credit: CBS News

The weird weather phenomenon comes at a pivotal point in the growing season. Farmers should keep an eye on their crops as the mercury drops, agronomists say.

“The low temperatures are going to slow the rate of crop development,” said Jeff Coulter, Extension corn specialist at the University of Minnesota. “In some cases, low temperatures just before pollination can cause silk balling, but that is not very common and most of the corn in Minnesota is not far enough along for this to be a concern.”

Should crop development be delayed that would, in turn, delay crop maturity and likely lead to less time for in-field  drydown of grain in the early fall when weather conditions usually are more favorable for drying, Coulter said.

However, “a few days of cooler temperatures shouldn’t have a huge impact,” Coulter added.

Corn crops in the lower Midwest, where plants are pollinating or close to pollination, could see yield losses, said Denny Cobb, senior agronomist with Beck’s Hybrids of Atlanta, Indiana. A similar cool spell that occurred several years ago caused kernel set development problems, he said.

“I think we took a 20-30-bushel-per-acre hit,” Cobb recalled. “We’re keeping our fingers crossed that the duration of this cool weather is not too long and doesn’t have the lasting effects that had in the past. I’m usually the eternal optimist but this is something we’ll have to keep on our radar.”

The other primary Midwest crop – soybeans – should come out of the cold snap in good shape, said Shawn Conley, Extension soybean and wheat specialist at the University of Wisconsin.

“At this growth stage – pre-pod set – there should be little impact,” Conley predicted.

By Steve Leer

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