HI and welcome!
I can't speak to that particular week in July; we tend to do the last week of July/ first week of August.
But Disney in summertime is amazing!!!!
Yes, as everyone will tell you, it's hot and humid... no surprise there. But the parks are open for EVER each day. Our plan, and the plan of lots of other summertime visitors, is to be at the parks half an hour before they open (AKA "rope drop".) We go in with a plan, knowing which rides we want to hit right away. I'm our "fastpass runner"-- I take each of our tickets and go alone to our first Fastpass attraction. I get each of us a Fastpass, then meet the rest of the family at an agreed upon place. (For example, with a 13 year old, you might want to have someone get FPs for Space Mountain, then meet the rest of the group at Big Thunder Mountain. Do Big Thunder and Splash Mountain, then use that Space Mountain FP. Within less than an hour, you will have knocked off three of the BIG rides that will have huge lines later in the day. Yes, it's a bit more running around for me, but it pays off big time.)
By around 1 pm, the parks are packed and it's VERY hot and humid. At that point we head back to the resort for an afternoon in the pool. By getting to the parks at rope drop, we've already seen a lot of the heavy hitters, and tempers are always short if we overstay our welcome-- the heat and the lines simply make it not as much fun. A few hours of swimming solves that. Then we have dinner, and spend the evenings in the parks, enjoying a slower pace.
A few other summertime hints: Invest in one or two Mistymate misters
http://www.amazon.com/MistyMate-100...098&sr=8-2&keywords=mistymate+personal+mister . They're a Godsend in the summer!!!!
And go to either
www.gardengrocer.com or
www.wegoshop.com and have water, park munchies and breakfast foods delivered to your resort. The water is key; it's exhorbitant in the parks.
Have fun planning!!!