Heavy rain across the eastern US soybean belt may add to yields already forecast at records in Illinois, Indiana and Ohio.

Cropli monitoring points in the three states took about five times their normal rainfall in the first half of August — all of it after the US Department of Agriculture closed the survey behind its first yield forecast of the season.

The rain fell through pod set and pod fill, the stages that decide how many seeds the plant carries and how heavy they finish. Cool, wet weather at that stage builds yield, meaning the downpour may give a further lift to the department's numbers.

The 12 August forecast put Illinois at 67.0 bushels an acre, Indiana at 62.0 and Ohio at 58.0, a record for each state. The national yield was trimmed 0.3 bushels from the July projection to 52.7, below last year's record, and production of 4.52bn bushels rests on a harvested area revised up 1.4m acres to 85.8mn.

[chart slug="us-soybean-podfill-rain-state-yields"]

Pontiac, in Livingston County, Illinois, took 183.9mm of rain between 1 and 15 August against a 1991-2020 normal of 32.2mm for those dates. Only one complete August in 86 years of record was wetter than that fortnight alone, according to ERA5 reanalysis data accessed via Cropli. Oxford, in Benton County, Indiana, took 178.5mm and Greenville, in Darke County, Ohio, 181.6mm, both about five times normal.

[explore layer="origin-chart" originId="soybean-united-states" pointId="usa-soy-mclean" tab="rainfall-deficit" snapshot="es_ffb897543b90d1c2" title="Rainfall against the 30-year normal, Pontiac, Illinois" subtitle="Cumulative precipitation at the Pontiac soybean monitoring point, against the 1991-2020 baseline"]

The fortnight was mild as well as wet, with daily maxima 1.3C below normal at Oxford and 0.6C below at Pontiac; no day reached 32C at any of the three points. The ground had room to take the water — USDA rated topsoil moisture surplus at just 6 per cent in Illinois and Indiana in the week to 9 August — and the crop was running ahead, with 74 per cent setting pods that week, five points up on both last year and the five-year average.

A great blue heron stands in floodwater covering the edge of a soybean field in Ohio

The deluge came after the USDA gave a clean bill of health for the majority of the crop. USDA rated 62 per cent of the crop good to excellent in the week to 9 August, a point lower than the week before and again ahead of the heaviest rain. Illinois and Ohio stood at 59 per cent and Indiana at 65, in the middle of the state table. Iowa led the country at 77 per cent, having taken three times its normal rain at Le Mars.

The rain came fast at the eastern edge, where Dayton, about 65km south-east of the Greenville point, set a daily rainfall record on 11 August. "A RECORD RAINFALL OF 2.07 INCHES WAS SET AT DAYTON OH TODAY," the National Weather Service office at Wilmington said in a statement quoted by the Dayton Daily News, which put the previous record at 1.86 inches, set in 1915. The Greenville point recorded 58.2mm the same day, and Darke County was under a flood warning two days later.

The same fortnight left the western and northern belt relatively dry. Redwood Falls, in south-west Minnesota, took 16.3mm, 38 per cent of normal and the second-driest first half of August in the 86-year record, with Madelia at 56 per cent and Sandusky, Michigan, at 51 per cent. USDA has already cut Minnesota's forecast yield to 48.0 bushels an acre from 52.5 last year, and rated North Dakota the weakest state in the country, at 31 per cent good to excellent.

[explore layer="origin-chart" originId="soybean-united-states" pointId="usa-soy-redwood" tab="rainfall-deficit" snapshot="es_ab8c67135df81e69" title="Rainfall against the 30-year normal, Redwood Falls, Minnesota" subtitle="The dry half of the belt: cumulative precipitation against the 1991-2020 baseline"]

"It appears to be a busy week across the Corn Belt as the weather pattern is really setting up to bring round after round" of storms, John Baranick, a DTN meteorologist, wrote on August 10.

Any extra bushels appear to be landing amid returning demand. China took 10.8mn tonnes of US soybeans in the first half of 2026, half of all US export volume and up from 5.9mn tonnes in the same months of 2025, according to US Census Bureau trade data accessed via Cropli. It bought none at all in the five months from June to October last year. Total US exports fell to 37.4mn tonnes in 2025, the smallest since 2011.

Ben Brown, an agricultural economist at University of Missouri Extension, told Brownfield Ag News on 5 August that the buying was encouraging but not unusual for the time of year. "They're usually buying at this point, this is a good sign," he said.

[explore products="1201" flow="exports" view="chart" partner="CN" period="monthly" metric="quantity" years="2022-2026" title="US soybean exports to China, monthly" subtitle="Tonnes shipped, 2022 to June 2026 - five consecutive months at zero in 2025, then the return"]

The August balance sheet added 39m bushels to 2026/27 supplies on the acreage revision, and raised ending stocks by 10m to 320m. Crush, the processing of beans into meal and oil, was up 30m at 2.78bn. USDA left the season-average farm price at $11.40 a bushel.

The Crop Progress report for the week to 16 August, the first official measurement taken after the rain, is released after 4pm eastern time on Monday. The September Crop Production report will be the first of the season to count the crop in the field rather than ask growers what they expect.