Few things say summer in America more than buttery corn on the cob, but as summer temperatures climb to unprecedented levels, the future of sweet corn may not be so sweet. New research shows sweet corn yields drop significantly with extreme heat during flowering, especially in rain-fed fields in the Midwest.Few things say summer in America more than buttery corn on the cob, but as summer temperatures climb to unprecedented levels, the future of sweet corn may not be so sweet. New research shows sweet corn yields drop significantly with extreme heat during flowering, especially in rain-fed fields in the Midwest.