As the 2026 crop year winds down, the effect of record-setting warmth during the reproductive time frame is starting to show up.

And warm it has been: July was the warmest on record (1895 to the present) for the contiguous U.S., with an average temperature of 76.9 degrees Fahrenheit. That figure is even warmer than the Dust Bowl years of the 1930s. Above-average temperatures covered the entire Lower 48 states. All states had temperatures in the warmest one-third of their July temperature records. No state had near- or below-average temperatures. (Information provided by the National Centers for Environmental Information, a division of NOAA.)

In Nebraska, the heat's adverse effect on corn is dramatic. Corn in fields watered by irrigation is showing incomplete kernel development, with sizeable portions of the cob completely bare. University of Nebraska-Lincoln agronomy professor Patricio Grassini has seen this condition frequently this season.

"High temperatures during the end of July and early August may likely explain it, since density was typical and there were no problems with water, nitrogen, diseases, etc.," Grassini said in an email.

The lack of completely filled-out ears of corn leads to prospects for below-average irrigated corn yields. The Aug. 25, 2026, update of the UNL Hybrid-Maize Yield model calls for " ... the probability of below-average irrigated yields, particularly in eastern and southwestern Nebraska and Kansas."

This is significant in Nebraska, where almost three-quarters (74%) of corn production is due to irrigation. In 2025, Nebraska was the No. 3 state in corn production, trailing only Iowa and Illinois. Nebraska produced 2.03 billion bushels (bb) of corn, with a yield of 194.0 bushels per acre (bpa). Applying the 74% proportion, irrigated corn amounted to 1.5 bb. But this year, conditions do not appear to favor a repeat of that achievement.

"I have been scouting fields this year to estimate yield, and (it) does not look like it will be a big crop for irrigated corn," Grassini said.

The UNL Hybrid-Maize irrigated corn analysis notes that the final months of the 2026 growing season are evolving like 2023, "... when the above-normal temperatures led to a shortened grain-filling period."

Full details on the 2026 corn yield outlook from the Hybrid-Maize Corn Yield Model are available here: https://cropwatch.unl.edu/….

Bryce Anderson can be reached at bryce.anderson@dtn.com

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