As Chicago temperatures today and tomorrow will likely hit 35°C, I find myself looking forward to October. While temperatures will undoubtedly be lower then, we may not actually have a very interesting leaf season:
Deciduous trees (trees that lose their foliage in the winter) are sensitive to the increasing length of night during the autumn. When the hours of darkness reach a threshold value, fall colors begin to appear. The U.S. National Arboretum says, "Because the starting time of the whole process is dependent on night length, fall colors appear at about the same time each year in a given location, regardless whether temperatures are cooler or warmer than normal." However, drought stress during the growing season can cause leaves to fall before they have a chance to develop fall coloration, and that will be the likely effect of our drought: bland fall colors.
The one, single benefit related to all this heat and drought: we're having the third-sunniest July in history.