We went last June and have plans to go this June as well. Yeah, it's hot, but a good hat, some good sunblock, proper dress, and a lot of water will make combating the heat a little more bearable. Just build in some rest stops throughout the day and you will be fine. Hit those indoor, lengthy rides/attractions (Ellen's Energy Adventure, Nemo the Musical, etc....) when the heat gets up to have an extended cool down with the bonus of seeing an attraction. And, like others have said, head back to your resort/hotel in the middle of the day for pool time/lunch/rest.