Dry weather reduces corn yields more than wet weather increases them

Weather during the growing season is critical for the development of the U.S. corn crop. In particular, weather in July tends to be the most important factor in the determination of corn yields. A corn yield model based on historical data covering the past 25 years provides estimates of the effects of weather and other factors. When other explanatory variables in the model are held constant, the model illustrates that the response of corn yields to variations in July precipitation is asymmetric—reductions in July precipitation below its average result in larger declines in corn yields than the gains in yields resulting from equal increases in July precipitation above its average. This chart is from Weather Effects on Expected Corn and Soybean Yields, FDS-13g-01.