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A Corn Belt Killing Freeze to Arrive in a Week

Impactful Frost Projects to Arrive in Parts of the Midwest on October 10-11.

DES MOINES, Iowa -- Portions of the Midwest felt cooler temperatures on Thursday morning, sparking concern about frost among farmers.

Temperatures dipped toward freezing in parts of western North Dakota, South Dakota, and Nebraska early on Thursday.

Thursday’s False Alarm

With moisture concerns already in farmers’ heads, potential frost added to the weather-related stress. Fortunately for Corn Belt farmers, the frost was close to striking, but it ultimately avoided most of the region. 

“I don’t think it was generally low enough for there to be any problems,” says AccuWeather meteorologist Dale Mohler about Thursday morning’s temperatures. “I see some 32s, 33s in eastern North Dakota, but most places were mid- to upper-30s in northeast South Dakota on up toward northwest Minnesota.”

Mohler also points out the lower temperatures lasted for around an hour, which has less of an impact compared with a three- or four-hour period.

For temperatures to begin causing damage, it has to sink below 30°F., says Mohler. 

The National Weather Service lists a frost occurring as temperatures fall between 36°F. A freeze is involved when temperatures dip between 28°F. and 32°F., and a hard freeze can happen below 28°F., according to the National Weather Service. 

Weekend Outlook

After Thursday’s scare, the short-term view looks unfavorable toward any potential Midwest frost. 

“I don’t think there’s really much to be concerned about through the weekend and into early next week,” Mohler says. 

Monday morning could generate more frost chatter in Minnesota and Wisconsin, but Mohler expects temperatures to stay in the range of 33°F. to 34°F. as the low.

Dakotas and Minnesota Frost Dates

On Tuesday, projections revealed October 13-18 as the target window for frost in the Corn Belt, but Mohler bumped those projections up.

“There’s an air mass coming down next Thursday (October 10) or Friday that looks a little colder than any of the first two — the one [Thursday] morning and the one Sunday, Monday,” Mohler says. 

The air mass could produce a frost in the Dakotas on the morning of October 10 and shift to Minnesota and Wisconsin on the morning of October 11. 

Mohler thinks temperatures could fall to 28°F. or 29°F., but he says it will likely remain in the northern portion of the Corn Belt. 

The air mass creating the October 10-11 frost potential is likely to only last during that period. A majority of the three states avoided an early frost, but an October 10-11 frost could still create problems with harvest behind schedule. 

South-Central Minnesota

In Minnesota on the week ending in September 29, the USDA reports 5% of soybeans have been harvested and 22% of corn is mature in its crop progress report. 

The 22% maturity total ranks 18 days later than last year and 14 days behind the average. The soybean harvest is behind last year by 15 days, and 2019 is 11 days behind the average. 

For south-central Minnesota farmer John Mutschler, the frost is less of a concern compared with the soggy field conditions.

“Our corn is 100% mature,” Mutschler says. “We’re just waiting for it to dry down. It has reached black-layered maturity, but like I said, we’re just waiting for it to dry out before harvesting — and for the ground to dry out.”

Part of the reason Mutschler’s corn reached maturity before a majority of the state is because of the timing during planting season. Mutschler says corn and soybean planting finished by May 15 this year with most of the corn planted in the first week of May.

“I’m not very concerned at all [for the frost], but we are in a much different situation here in south-central Minnesota than in the rest of the Corn Belt,” Mutschler says. “We’re not looking too bad, but you don’t have to go too far east, west, north, or south, and it’s going to be devastating.”

Sperling, Manitoba, Canada

North and South Dakota join Minnesota in falling behind on harvest (4% of soybeans harvested in North Dakota with 15% mature corn and 1% of soybeans harvested in South Dakota with 29% mature corn, per USDA reports).

Even farther north, farmer Curtis Hiebert faces a similar challenge in Sperling, Manitoba (about 200 miles north of Fargo, North Dakota).

“We’ve had a touch of frost here already, but it hasn’t killed the corn yet — just crisped some top leaves,” Hiebert says. “I think if it [a major frost] happens in a week, we’ll then we’ll be happy.”

Hiebert says his corn is close to being ready for harvest, but it needs a little more time. He says his soybeans and edible beans are more than ready to be harvested, but rain has kept it in the field.

Despite the wetness with the crops, Hiebert says he doesn’t plan on letting the corn dry down for spring.

“The water is more of an issue than the frost right now, where that’s our biggest problem,” Hiebert says. 

Agronomy Insight

Dave Mowers, a consulting agronomist for GMS Labs and AIM for the Heartland, shed some light on the different temperatures and the meaning behind them in terms of crops. Mowers says hard-freeze range temperatures don't always affect crops, and temperatures about freeze-range can affect them. Mowers cites the microenvironment, including relative humidity and other variables as factors in the level of damage crops take with lower temperatures. 

While there are exceptions to a killing freeze, Mowers says it generally causes major damage in corn that's not completely mature.

“If it’s a killing freeze, it can really cause a lot of damage,” Mowers says. “It affects the grain quality, obviously, and it just slows the drying process down — if not ceases it... Light test weight and slow to dry, those are the two things that farmers need to worry about.”

Mowers says the combination of a wet spring followed by a wet harvest and a frost on the horizon has created as uncertain of a year as he’s experienced in his 48 years around agriculture. 

The tough year reminds Mowers of 1974, when crops struggled to be planted in the spring due to wet conditions, but 1974 saw a killing frost in early September unlike 2019. Mowers says 2019 got off to a much later start than 1974, but 2019’s had a stronger finish. Regardless, Mowers doesn’t expect a huge volume of crop.

“It’s going to be one of those years we’ll write down in the history books, and probably won’t ever see anything like it again,” Mowers says.


Story written by Trevor Holbrook


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