Want to know how your corn will grow this year? Watch the Pacific Ocean.

That was Eric Snodgrass’ message for Midwestern farmers heading into the 2024 growing season.

“It’s going to come down to the story of what the atmosphere does to the ocean temperatures — and that affects how we grow corn,” says Snodgrass, senior science fellow for Nutrien. “Everything is connected.”

The Midwest experienced an El Niño winter, which is typically followed by a collapse of El Niño into the ENSO-neutral phase, and sometimes even La Niña, by summer. So the question is, how quickly will we transition to La Niña? This will impact everything from summer rains to the severity of hurricane season.

Snodgrass points to history. Since 1950, nearly every year the Corn Belt has had an El Niño winter that crashed by summer into a La Niña, the most frequent summer weather pattern was hot and stormy.

“But what’s odd is that there are years in the mix, like 1983 and 1988, where that transition resulted in widespread Corn Belt drought. But 2016 was also a transition year, and the result was a lot of summer storms in the Midwest,” he says.

But the overall takeaway from history: If there was drought in those summer La Niña years, it usually was in the Southern Plains, the Delta or the Southeast. The Midwest was hot and stormy.

Model material

Look at the weather forecast models, and it’s a completely different story for 2024.

“They build the drier conditions into the Western Plains by May and June and July; then it creeps across the Plains into the Midwest by August, running all the way into Illinois and Indiana,” Snodgrass explains. “And by August and September, it looks like it did in 1988, where it’s hot and dry in the Corn Belt, while the Cotton Belt is wet and stormy.”

So, which forecasting technique will be right?

Snodgrass is confident El Niño will give way to La Niña by fall. If it arrives by July, drought risk in the Midwest goes up by a lot.

“If ocean temperatures go really, really cold between now and July, I’d be very surprised if we didn’t have major drought episodes in the Corn Belt,” he adds. “Like, by August — a critical month.”

That’s what happened in 2012, 1991, 1988, 1983 and 1976.

Oceans, atmospheres and markets

Snodgrass switches his meteorology hat to a marketing hat and ponders a possible huge yield response for a hot, stormy summer with modern hybrid technology.

“What if, instead of Corn Belt or Cotton Belt drought, there’s a massive ridge of high pressure over California, and all the heat is in the Western U.S. — so we don’t have excessive heat in the Midwest and we have plenty of rain?” he asks. “What if we don’t just hit USDA yield targets, but we blow ‘em out of the water by 3 or 4 bushels?

“That’s terrifying, because that might give us a large carryout on corn, and prices could slip farther.”

Historically, Snodgrass adds, the largest price change in corn and soybeans due to weather conditions typically occurs from June 20 to July 20, based on weather scares around pollination and grain fill.

“That’s the really pivotal time when the atmosphere is going to show its ugly head and could give us a weather premium in the market,” Snodgrass says.

El Niño and La Niña defined

El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the Pacific Ocean. That pattern shifts back and forth irregularly every two to seven years. That brings predictable shifts in ocean surface temperature and disrupts rain and wind patterns.

El Niño. The ocean surface warms in the Pacific Ocean. The polar jet stream is typically farther north than usual, while the Pacific jet stream tends to remain across the Southern U.S. In winter, that typically results in above-normal temperatures in the Midwest, with fewer cold air outbreaks.

La Niña. The ocean surface cools in the central and eastern tropical Pacific Ocean. The polar jet stream is typically further south than usual and increases chances for below-normal temperatures and wetter-than-normal conditions across the Midwest.