We were there July 1-7. It was hot and humid with scattered thunderstorms. And yes, it was crowded! Having said that, it is very doable with a plan. Drink plenty of water. We took a soft-sided cooler with us in the parks and carried some water in that. In that cooler we also had a ziplock baggie with ice and couple of microfiber handtowels that we used to cool us off when we took breaks. This helped quite a bit. If you don't want to carry a cooler, you can get free cups of ice water at cs places. EMH can be hit or miss. We did a pm EMH at AK that was great! Low crowds there and we stayed till closing! We did the 4th of July fireworks on the 3rd. That was all we did at the MK that night- it was packed, so we went back to the hotel to swim. I have been told it's even worse on the 4th. IIRC, there were pm EMH on the 3rd and early EMH on the 4th at MK, so we went on the 5th. We had an ADR for CP at 8:05 am and was waiting for the rope drop at TL just before 9:00. The crowds that morning were low and we managed to get a lot done (including some things twice) before noon. When we came back later that evening, the crowds were heavier, but not too bad.
If you're using Disney transportation, allow for a little extra time. Make ADRs if you plan to eat at TS restaurants. Take advantage of the fastpass system as much as possible. That's a HUGE help with the more popular attractions! Bring rain ponchos- the parks tend to thin a bit when it rains. We had a big storm come through late one afternoon/early evening. DH and I had thought about cancelling our CM ressies but we went anyway. After dinner, it was sprinkling off and on, so we thought we would see what the crowd level was like at MK. It was awesome! Very few people there! My 7yo DD was able to watch Wishes w/o anyone blocking her view. We also took mid-day breaks almost every day. For us, it really did make a difference.
I will admit, I was a little aprehensive about going in July because of the heat and the crowds, but it was the only time my DH could go, so we did and have no regrets. With a little planning and being prepared, it can be very manageable.
