We always go around that time, either right before July 4th or right after. There really is no significant difference between that time period, and it will be VERY crowded. Without utilizing fast pass, the more popular rides will have upwards of 60 minutes waits, with some going up to 90 minutes. Dumbo is practically unavailable, after 9:30 due to 45 - 60 minute waits. The heat is oppressive, but we take mid-afternoon breaks back at the resort swimming and napping are musts! We love the summer and the crowds and heat don't bother us, but we do careful planning to help minimize the heat and crowd impact.