July time of year, most likely you will be hit with afternoon thundershowers as opposed to all day drenches.
The MK has the best covering, it was really designed with rain in mind.
In the afternoon keep an eye to the sky, if you see dark clouds looming, try to “beat the crowds” to someplace where you can occupy your time.
If at Disney Studios, I make a beeline to the lounge next to the prime time cafe and grab a stool at the bar. When the rain starts you can watch the wet people crowd in.
If at the MK, head out to the Monorail and do a hotel tour (their are shops etc to look at, and even a bar or two that are open during the day )
Schedule restaurant ADR’s for around 3:30 or so, while not full proof you may find yourself eating while it is raining and by the time you are done, the rain will have stopped. The crowds would have dispersed so you can get some quality ride time in.