Mother Nature has not been the most cooperative with U.S. farmers this spring. And as that optimal planting window begins to narrow and yield worries increase, more market focus is turning to USDA’s national corn yield estimate.

Most farmers who are fully planted – and even more who aren’t quite finished – are beginning to look at the probabilities of where that final corn yield estimate will end up. Specifically, let’s look at the biggest factors farmers can expect to impact 2024 national corn yields and what that will mean for 2024/25 marketing plans.

Planting timeliness

Seeds aren’t the only thing sown during planting season – many growers over the past month may have developed worries about planting within the optimal yield window. As many farmers experienced in 2019, severe planting delays can stunt yield potential.

Through the week ending May 12, USDA’s crop progress report found that 49% of the nation’s corn crop had been planted, up 13% from the prior week but still lagging 5% behind the five-year average for the same reporting period.

Corn planting speeds are now equal to those of 2022 for reference. Monday’s corn planting data came in aligned with pre-report analyst estimates, so the data did not substantially rock the corn markets during the early morning trading hours.

Related:Soggy fields frustrate eager farmers

The “I”-states continue to lead the lag behind historical paces and farmers in the region are growing increasingly frustrated by the lack of planting progress they have been able to make over the past couple weeks. And some of that frustration is likely justified.

Academic papers vary on what is the exact date that the yield window closes for corn this time of year. USDA economists circle May 15 as the date by which current year plantings should equal the most recent 10-year average – around 80% complete.

At any rate, Monday’s data shows that we are running behind, though the situation is nowhere near as dire as in 2019. As we’ve seen in recent years, minor planting delays don’t always have an outsized impact on yield development - USDA did not deviate from its trendline yield estimate in the June 2022 WASDE update when sowing speeds were similar through Week #19 during the growing season.

In fact, corn yields can derive strength from other weather factors that can help to offset losses in years when part of the crop may have been planted outside of the optimal yield window. A University of Illinois analysis posits that late planting is only the third largest factor for corn yields. But the top and bottom two factors are going to be timelier for growers across the Heartland over the next month or two.

Related:Crop progress: Corn plantings fall below five-year average

July rain and temperatures

Corn crops typically undergo peak reproductive phases in mid- to late July. The crop is especially sensitive to moisture and heat conditions during this time when it is expending its peak energy requirements, so it should not come as a surprise that economists and analysts agree that July precipitation is the most critical component to corn yield success.

A University of Illinois Farmdoc Daily article published last fall suggests that July precipitation volumes can play an outsized role in yield development. On average, just under four inches of rain falls in July. The U of I model factors one standard deviation above and below the average, which results in a range of just shy of three inches to slightly less than five inches as an optimal range of total monthly rainfall to maximize corn yields.

Under this model, if July rainfall averages fall below this range, a 12.7 bushel-per-acre penalty will likely be applied to national trendline corn yields by the time 2024 yields are finalized in the following January. An average of five inches of July precipitation is optimal for maximum yields. It would take an excess of six inches of average July moisture to reduce yield prospects.

Over the past 14 Julys, national rainfall has averaged 2.9 inches. In 11 of the last 14 years, July rainfall has topped 2.74 inches or higher, meeting the model’s requirements for positive to neutral yield impacts.

The study also notes July temperatures as being the second most significant factor in corn yield potential. We saw this play out last year when moderate July temperatures compounded with late July showers to set a record national yield of 177.3 bpa.

June weather – a non-starter?

June temperatures and precipitation were among the two least impactful factors influencing corn yields, just ahead of April temperatures. So if you have been worrying about weather impacting yields, that is likely going to be a bigger concern in July than in June.

The June 30 USDA acreage report typically provides some volatility – particularly if farmers opted for more corn acreage instead of soybean acres this spring as USDA indicated in its Prospective Plantings report.

But if you use the month of June to nail down 2024 expenses, budgets and cash flows so you have a clear break-even price to work off of through the remainder of the summer months, the market volatility will present a less daunting challenge for your operation as corn yields develop throughout July.