Warming temperatures in U.S. Corn Belt expected to continue into next decade

According to weather data from National Aeronautics and Space Administration (NASA), temperatures in the Corn Belt, a region spanning across Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, and Wisconsin, have trended higher in recent years and are projected to continue to rise through the end of this century. Two measures can be used to capture how rising temperatures affect crops’ growth—growing degree days and extreme degree days. Growing degree days describe the beneficial temperatures in a day that allow a plant to grow and mature. With rising temperatures, the growing degree days for corn and soybeans increase. A crop’s exposure to added growing degree days is not necessarily harmful; after all, crops need heat and precipitation to grow. However, extreme degree days, which refer to temperatures throughout the day in excess of 30 °C (86 °F), cause heat stress that is harmful for a plant. Each decade since 1992, both growing degree days and extreme degree days have steadily increased with rising temperatures in the Corn Belt, where about 80 percent of all U.S. corn and soybeans are grown. In the decade leading to 2032, both measures are projected to continue to increase. This chart first appeared in the USDA, Economic Research Service report, Estimating Market Implications From Corn and Soybean Yields Under Climate Change in the United States, published in October 2023.

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