Using principal component analysis, a climate index is developed to estimatethe linkage between climate and crop yields. The indices based on threeclimate projections are then applied to forecast future crop yieldresponses. We identify spatial heterogeneity of crop yield responses tofuture climate change across a number of U.S. northern and southern states.The results indicate that future hotter/drier weather conditions will likelyhave significant negative impacts on southern states, whereas only mildimpacts are expected in most northern states.