Frost Forecast Threatens Corn And Soybeans This Week

Frost isn’t a four-letter word, but it sure seems like one at this point in the growing season, when corn and soybeans are packing on starch and finalizing yield.

Brett Walts, meteorologist with BAMWX.com, predicts a potential frost for multiple days now for parts of the north-central U.S. and southern Canada. He says this is the earliest he has ever forecast freezing temperatures.

“Much of North Dakota is under that risk, and northern parts of Minnesota as well. For central Wisconsin I wouldn’t 100% roll out the risk in outlying and low-lying areas, even into parts of South Dakota and southern Minnesota,” Walts tells Chip Flory, host of AgriTalk.

A corn-killing freeze occurs when temperatures dip to 32 degrees Fahrenheit for four hours or 28 degrees for minutes, according to an online article by University of Minnesota Extension. A killing freeze can still happen with temperatures above 32, especially in low and unprotected areas when there’s no wind.

How much corn yield could be lost to freeze is tough to predict, but it could be significant, according to Troy Deutmeyer, Pioneer field agronomist.

“It is extremely difficult to predict but corn around half-milk line that dies will have yields cut around 10% according to older studies. With today’s late-season grain fill and kernel flex I feel the number is closer to 15%,” he says in a post to X. See his full comments below.

“Between the fourth [of September] and the eighth, it’s going to be pretty consistently down into the 30s and 40s for temperature lows in that region,” Walts says.

Timing-wise, Walts anticipates the frost threat is a multi-day risk, moving in by late tonight or early Thursday and staying through Sunday.

Corn Is Vulnerable In Cold, Wet Conditions

“We’d talked about how the corn crop needs some cooler temperatures, but these are not the kind of cooler temperatures we were talking about, that’s for sure – especially up in North Dakota, northern South Dakota, into central Minnesota,” Flory says.

(University of Minnesota Extension)

“There’s a lot of corn up there that could still benefit from a lot more growing season,” he adds “If we get into this prolonged period ofcold temperatures, even if we don’t see a frost, it can have a negative impact on the yield potential up there. No question about that.”

Walts says as the calendar moves past Sept. 10, temperatures will moderate for several days, but he doesn’t expect the warming trend to stay. Instead, he says it will be short-lived, with another cold front arriving in the same region around September 15.

Rain Could Add To The Frost Problem

Walts adds there is the likelihood that some of the areas under the frost watch could endure bouts of rain, though he anticipates they will be patchy.

“It’s going to be these messy, scattered showers and storms along these fronts,” he notes. “I would say areas that could pick up maybe more than a half an inch of rain will be across Minnesota, maybe northern parts of Iowa. But I think the further south and east you go across Illinois and Indiana, eastern Missouri, the messier that it is, and more likely some areas will be skipped over.”

Some of the skipped over regions include the far Northwest and West, both of which are likely to remain rain-free over the next week, Walts adds.

His complete forecast is available on AgriTalk here:

Your next read: Southern Rust Set To Take Big Bite Out Of Midwest Corn Crop?