The Influence of Extreme Weather on Corn Yield: A Gini-Index Based Analysis of SPI and Agricultural Production on U.S. Corn Belt

Rising temperatures and more extreme weather are increasing risks for crop production in the U.S. Corn Belt. This study examines how drought and heavy rainfall affect county-level crop production from 2000 to 2023. We use weekly Standardized Precipitation Index (SPI) values from April 1 to August 31 to track changes in moisture during the growing season. A Gini index approach measures how sensitive each county is to extreme weather. We created a detailed map showing which counties are more affected. The results show that counties with high drought sensitivity do not always have low yields. Some maintain stable production even under extreme stress. We also find that neighboring counties can show very different responses, even when exposed to similar conditions. This suggests that local management practices and farming decisions play a major role in shaping outcomes under extreme weather.