Ag Weather Forum

The weather forecast of a hotter and drier pattern for portions of the Western Corn Belt during the last part of July into early August calls to mind a look at corn crop condition ratings this crop year 2024 along with the top DTN weather analog year 2020.

The year 2020 was a year when the Pacific Ocean sea surface temperature and atmospheric upper wind pattern changed from the warm-ocean El Nino to the cool-ocean La Nina. The ocean region analyzed for El Nino or La Nina is the region around the equator from the west coast of South America (Peru) to the International Date Line. The entire pattern is called the El Nino Southern Oscillation (ENSO). The Pacific ENSO began 2024 in El Nino and is evolving to La Nina, with La Nina expected to be in effect during the Northern Hemisphere fall months of August-September-October.

A look at corn conditions for the Top 5 production states in the USDA/NASS weekly Crop Progress reports this year and back in 2020 shows quite a few similarities. In 2020, the week ended July 19 had the following good-to-excellent condition ratings for the Top 5 states (listed alphabetically): Illinois 63%; Indiana 59%; Iowa 80%; Minnesota 83%; and Nebraska 68%. U.S. corn crop ratings had a 69% good-to-excellent total.

In 2024, the week ended July 21 has these corn crop ratings in the Top 5 production states: Illinois 75%; Indiana 69%; Iowa 75%; Minnesota 58%; and Nebraska 75%. U.S. corn crop ratings have a 67% good-to-excellent total. The takeaways for this observer are that the Eastern Corn Belt states (Illinois and Indiana) have higher ratings at this point in the season in 2024 versus 2020, and Minnesota has a rating that is 25 percentage points less in 2024 compared with 2020. That lower Minnesota rating number is directly related to the impact of flooding and storm damage.

This year 2024 and top DTN analog year 2020 are also comparable on crop progress. The report for the week ended July 21, 2024, showed corn silking at 61% with 17% in the dough stage. Back in 2020, the report for the week ended July 19 indicated corn silking at 59% with 9% in the dough stage.

Markets will, of course, closely track the evolution of the crop weather pattern as corn goes through the final almost-40% of silking and then through the grain-fill stage. That's where the onset of hot and dry conditions can take away bushels quickly. The welfare of the northern crops will be key in this regard; in the Top 5 production states, Minnesota's corn silking pace was only 38% as of July 21, 2024 -- 16 percentage points less than its five-year average. The other Top 5 production states are all ahead of the average corn silking pace.

The potential for additional storm damage also commands awareness. The central U.S. has already experienced derecho wind events during this crop season. Looming in the collective market memory is the hallmark weather event of crop year 2020 -- the Aug. 10-11 Midwest derecho -- which destroyed so much corn, especially in Iowa, that harvested acreage was lowered in official USDA production estimates at the end of the year. So, a nervous time is ahead for the U.S. corn crop with its potent coincidence to a historic analog year.

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

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