Two years that live in infamy among Midwestern farmers: 1993 and 2009. In both years, cold weather and wetter-than-average springs meant planting was delayed until June in many cases. And like many farmers, Frank Hopkins, Knoxville, Ill., watched his grain-drying bill skyrocket in 2009, thanks to a wetter-than-average harvest.

He and the majority of Corn Belt farmers avoided an early first frost both years, which granted them a few days beyond the average growing season to allow crops more time to mature. The average for the first freeze in central Illinois falls on Oct. 15, though it happened as early as Sept. 23 in 1995.

Hopkins acknowledges it’s a gamble this year, after another late planting season. “If you got planted in April this year, you’ve got decent prospects. An average or early freeze won’t cut off much yield. But the late-planted stuff is really just a crapshoot. You don’t know where it’s going to end up,” he says, noting that accumulating more rainfall through a late, dry summer is as important as the length of the growing season.

Hopkins planted his tile-drained and best-yielding acreage in April and expects good yields no matter when frost hits. The other half of his corn and soybeans didn’t get planted until June — and that ground is poorer — so Hopkins is hoping for a later-than-average frost for his area.

“If we had an early frost, it was going to be poor yields on late-planted stuff anyway, and it would basically dwindle it down to nothing almost, especially since it’s been so dry,” he says. “Although, if you did have the early frost, the markets would respond tremendously, so where’s the trade-off? Would you rather have a few more bushels and no frost or have frost with what bushels you’ve got?”

AccuWeather analysts recently predicted corn yields will decline 9.3% from 2018. That’s 5.8% lower than USDA’s August crop report forecast. AccuWeather predicts soybeans will yield 14.1% less than they did in 2018.

Late frost likely

But meteorologists offer a glimmer of good news. Models by the National Weather Service say there’s a 60% to 70% chance of a warmer fall than usual. Privately controlled models by both Nutrien Ag Solutions and The Climate Corporation point to the first hard frost date for most of the Corn Belt occurring later than normal.

“It’s an unusually strong signal supporting this prediction. It’s still a roll of the dice in our perspective, but it’s like the dice are loaded,” says Tony Eckel, senior atmospheric scientist at The Climate Corporation. “You’re more likely to get a warmer fall than normal, and that signal is fairly strong in our experimental models. That doesn’t mean everywhere will be warm. There’s still a slight chance that an area can be normal, or even cool. But that would be a surprising case.”

Eric Snodgrass, principal atmospheric scientist at Nutrien Ag Solutions, says climate history underlying the models they use show useful trends. In central Illinois, about a week to a week and a half has been added to the frost-free season.

“Our time scale now is last frost in April, first frost in October,” Snodgrass says. “That lengthening is part of a climatological signal that says we can get a little later frost, but the dataset is very noisy; it bounces year on year. When you average and fit a line to it, you do see we’ve increased the frost season over the last 30 years.”

When the El Niño system over the Pacific Ocean collapsed earlier this year, global wind anomalies went negative, “which means global winds have calmed down. When these models ingest that information, they automatically start to forecast a later frost, or at least, closer to climatology,” he says, referring to the 30-year average of first frosts.

Greg Soulje, meteorologist for “This Week in Agribusiness,” says minimal activity in the tropics also tamps down the possibility of a system obstructing the jet stream and pushing cold air into the Midwest.

“We think we’ll get an extended growing season, with the exception of parts of Michigan and maybe Ohio,” Soulje says.

Cold air that accumulates over Alaska and Greenland could be pushed into the Canadian Prairie and the Midwest by an upwelling of warm air from remnants of a Pacific tropical cyclone or other global weather-influencing events. Frosts are one-off events and can be spurred on once early in the fall. Even if temperatures don’t dip back below 28 degrees F for weeks, the freeze is often fatal to crops. And even if it’s slightly above freezing at 32 degrees, the damage of the cold is severe.

“If we keep the tropics quiet during this duration in the summer where we reposition the upper pattern in the atmosphere, we’re generally looking favorably for most locales in the Corn Belt,” Soulje says, concluding a majority of the region will increase its growing season by a week to 10 days. “In some areas, two to three weeks,” he adds.

Variability casts doubt

Snodgrass makes it clear the predictions of models are “half the story.”

“All of us are very well aware that forecasting a frost event more than maybe 10 days out is nearly impossible,” Snodgrass says, adding models are vital for determining probabilities and can be adjusted as new data becomes available. “In the season, you’ll probably see us meteorologists continually adjusting that prognosis. Frost looks like it’s going to be a little later, but there could be something that comes in and shifts all that around.”

Beth Hall, Indiana’s new state climatologist, says the two- to four-week time frame generates more reliable signals than looking months in advance.

“There’s so many different global fluid patterns of the atmosphere where we just don’t know enough to be able to say in August if this year’s first freeze, whether we define it at 32 or 28 degrees F, is going to be earlier or later,” Hall says. “There’s no confidence of the models, or even historical data, for us to be able to say something about 2019.”

Hall shares preliminary findings from a study where her team looked at historical periods in fall that dipped between 28 and 36 degrees. Some temperatures show a trend for a later freeze; some don’t.

“Problem is, there’s still such inter-annual variability on when that frost-freeze occurs that you can’t say if it occurred on Oct. 13 last year, it will be [Oct.] 14 this year,” Hall says.

In reflecting on his wet 2009 harvest near Knoxville, Hopkins says delayed frosts have their trade-offs. He bought a dryer the following year to reduce his drying costs, but he doesn’t think it will be “absolutely necessary” to have this year. His reasoning is that it’s been fairly dry in parts of Illinois in terms of accumulated inches throughout July and early August.

“If you had some early stuff planted, it’s all going to dry down normal,” Hopkins says.

Soulje says late fall and early winter have been trending wetter for Illinois and the rest of the Corn Belt.