As of September 27, 2026, the AIFS ENS indicates average daytime highs near 70°F and overnight lows around 59°F over the next five days across the core Corn Belt. Looking ahead, the AIFS ensemble precipitation looks widespread light to moderate, averaging roughly 1.22 inches in days 1–5 (heaviest in central Iowa (including the Des Moines area) (2.1 inches) and lightest in southeastern Iowa, central Illinois and northern Indiana (0.8 inches)), 0.38 inches in days 6–10, and 0.12 inches in days 11–15. ECMWF ensemble-mean 3-hour frames suggest light activity is already indicated in the next 12 hours (ensemble-mean ~0.09"); a broader light-to-moderate signal remains possible around mid-week. Harvest is underway or rapidly accelerating across the Corn Belt. Corn is largely at or past black layer (R6) and soybeans are at full maturity (R8). Field activities center on combining as grain reaches workable moisture. Prolonged wetness in parts of the western belt has also raised concerns about stalk integrity where mold or fungal growth has weakened hybrids. Weather now primarily affects harvest progress, grain moisture, field trafficability, and lodging risk in weakened standing corn. Through September 26, the wettest of the four Corn Belt quadrants on a 15-day basis was southwestern Iowa and northern Missouri at about 0.87 inches (normal near 2.02 inches, ~43% of normal); the last 7 days brought about 0.87 inches versus a normal near 0.96 inches. Harvest weather looks more workable across northwestern Iowa and southwestern Minnesota, northeastern Iowa, northern Illinois and southern Wisconsin, southwestern Iowa and northern Missouri, and southeastern Iowa, central Illinois and northern Indiana, supporting steadier progress where grain moisture is ready. Where prolonged wetness has encouraged mold or fungal growth on hybrid corn stalks, any stronger wind event would increase lodging and harvest-loss risk in vulnerable fields, so wind forecasts should be watched alongside soil trafficability. That days 1–5 wetting (about 1.22 inches belt-wide on average) would further slow fieldwork in already soft areas and keep harvest progress uneven.
