For the major grain crops, there is a need to better document the opportunities for existing genetic variation in phenology, temperature tolerance, and response to elevated CO2 to contribute to improved yield, especially in regions where temperatures are predicted to increase; that is, what will the TPE look like for future climates? Especially at the rainfall-limited edges of the current grain-cropping regions, temperature increases maybe such that novel genetic variation is required so that wheat and sorghum production, in particular, is still viable in most seasons.