All my trips have been in August - drink at least a full bottle of water prior to going to the park. Get well hydrated before leaving. Bring multiple bottles of water with you to parks, if possible freeze them the night before - they will melt quickly. Drinking water while at breaks or in line will help. If you have kids, push them to keep drinking. Try to do rope drop and stay til 1 or 2 pm, maybe returning in the evening. Get in as much as you can in the mornings, we always return to hotel during the afternoons to cool off and swim. Always duck into shops to cool off in the A/C when you can. Attractions like Tiki Room, Carousel of Progress, or other A/C indoor attractions are good as it heats up in the late morning / afternoon.