Like everyone else says, it is really really hot in July. You will need to fill up on a lot of H2O or else you'll be in trouble. Just stay hydrated and you'll be okay. Even teenagers like myself need a lot of hydration. The lines for Splash Mountain alone are about 1 1/2 - 2 hrs midday. The lines get VERY long. But don't be discouraged because July is a WONDERFUL time to go to Disney as you have EVERYTHING open. NOTHING is closed (intentionally at least).
Make sure to use FASTPASS to your advantage.
Make sure to use FASTPASS to your advantage.

The crowds will be horrendous!! Prepare yourself for 3 or 4 or mabye even5 hours for splash Mountain standing there in line when it is 120 degrees out staring at the sweating fat wrestler in front of you! The water parks will might close because they are at capacity! So will the parks!! Sience botteld water is expensive (aka 2.00 a bottle) all the parks will be squishin you in there like sardines so youll see 1 ride and then be exauhsted, hot and feeling like you are gonna faint. You wont be able to get food because the lines are so dang long. Nothin do to at hotels because the pools will be packed!! Just over spring break the Magic Kingdom closed because it was 100 over capacity!
so if your plans are flexible go in febuary or november


We really wish we could do Universal but we'll definitely do it next time!
Yes, it is hot - but many times it has been hotter back at home in Kansas then it was in Orlando! We use the early entries and the fastpass system to our advantage to beat the crowds and never seem to have any problems with long lines. Often times a thunderstorm will roll through late in the afternoon or early evening which sometimes cools things off when you go back to a park or out to another resort for dinner. We also use the little misty fans and always leave the parks shortly after lunch to go back to our resort to cool off in the pool. We love Disney in July and wish this summer wasn't our off year so we could be going back there again in just three months! You are lucky to be going and I think you'll do just fine with the heat and crowds! 