Last year, that's the week Hurricane Wilma went through!
We got there on a Saturday night. Sunday was hot and humid (85 degrees at least, maybe more - I was pretty uncomfortable). In the evening, we had a torrential downpour (I have never been in a rainstorm that heavy - it was amazing!). By Monday morning, we got the fringes of the hurricane, and they closed the park until 2:00 p.m. The rest of the week, it was very pleasant - virtually no humidity, and temps in the mid-to-high 70's. The only drawback was that it wasn't warm enough to hang out at the pool - just a little too cold.
So you never know what's going to happen. We wore everything from shorts to jeans, so in the week we were there, the weather changed a lot! Check the weather forecast right before you go. My advice is, pack a little of everything so you can layer if needed, plan to do laundry mid-trip (so you don't have to pack as many clothes), and have a great time!