Ag Weather Forum

United States corn planting was just under half done (49%) as of Mother's Day on May 12. That's five percentage points less than the 2019-2023 average of 54% planted. But a look at planting progress compared to the top weather analog years in this year of an expected Pacific Ocean change from El Nino to La Nina shows an even bigger lag.

The top two weather analog years identified by DTN's long-range forecast team are 2020 and 2010. Those were also years when the Pacific Ocean El Nino-Southern Oscillation (ENSO) pattern changed from El Nino (warm) to La Nina (cool) in a fairly short time frame. Both years had more corn in the ground across the U.S. than we see right now in 2024. In 2020, 67% -- just over 2/3 -- of the U.S. corn crop was planted by the second weekend of May. And in 2010, 81% of the U.S. corn crop had been put in by the second weekend of May.

Reviewing the top five corn-producing states shows some dramatic differences in progress as well. Iowa's corn crop is 57% planted as of May 12, but in the analog years, Iowa was almost finished at 91% in 2020 and 93% in 2010. Illinois, only 42% planted, trails 88% in 2020 and 94% in 2010. Nebraska's 55% planted pace is behind 79% in 2020 and 78% in 2010. Minnesota, 56% planted, is well under 89% in 2020 and 94% in 2010. Indiana's 36% planted pace compares with 51% in 2020 and 81% in 2010.

Those planting progress numbers become significant when looking at the corn progress timeline and how it matches up with the expected Pacific Ocean conditions. Slower planting progress means a larger portion of corn pollination will be pushed back into late July. This delay, in turn, suggests both corn pollination and grain filling might be happening at a time when expected hotter and drier conditions brought on by La Nina settle in over the primary U.S. corn growing areas.

The NOAA Oceanic Nino Index (ONI) indicates that La Nina in 2020 began in the July-August-September time frame. In 2010, La Nina showed up even earlier, in the May-June-July period. DTN's expectation that La Nina will begin in June or July places the expected start of La Nina in between those two, benchmark analog-year events.

Late-season heat, dryness and storminess affected corn yields in the analog years of 2020 and 2010 even with faster planting progress than in this current 2024 crop year. The slower rate of planting in a year with La Nina on the summer horizon brings more questions about if -- and how much -- the U.S. corn crop performance will be affected. The final estimate of the 2020 U.S. corn yield was 172 bushels per acre, almost 10 bushels per acre below an August estimate of a record 181.8 bushels per acre. The 2010 U.S. corn yield final estimate was 152.8 bushels per acre, more than 12 bushels per acre less than the August estimate of a record 165.0 bushels per acre.

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

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