We've gone several times in June and will be back this year, June 20-27. Be sure to use sunblock and hats, drink plenty of water, and invest in the misty fans. You might also want to tie a bandana around the strap of your bag or something. You can wet it in a fountain and use it on your face and neck to cool down. There are lots of spots in the park where you can get misted with cool water - take advantage of them to help with the heat. If your doing counter service meals, eat at off times to avoid the crowds. Staying hydrated is key - if anyone in your group doesn't care for the taste of the tap water at Disney, take the powdered drink packets to flavor it. That's all I can think of for now. Hope it helps.