I went in June just been, left the 11th from England. The first three days was a nightmare, we arrived in Sanford and the storm was unbelievable only walked three steps and was soaked through. It poured down in magic kingdom all the next day but we pushed through with out ponchos. The next day was animal kingdom we got there at 9 had fastpass for the lion king and the weather was beautiful not a cloud in sight. When we came out it was again another storm which we thought would pass so waited in a three hour line for dinosaur I believe only to find when we came out it was still heavily raining.
All the rides were shut as it was thunder and lightning so we sadly made our way back to the car. Same again the next day in universal but managed to make it till around 1pm without any storms. This was my third visit to disney world and the two previous times I had been in May with hardly any rain. At this point the trip was looking bleak and was only three days in. In a lucky turn of events after that the weather cleared up with maybe an occasional 5-10 minute shower midday but most storms or showers around 6/7pm. The parks were really crowded but we used the wdw app for iphones and had all our fastpasses pre booked for our favourites. I personally did not find it to be a struggle but that is most likely because i've never experienced the park empty!
I'm sure it will be fine just make sure to bring a poncho, although I preferred using a umbrella! Also i bought a Japanese sun parasol in Epcot and that saved me from some of the heat!
Booking trip for July with boyfriend, his first time experiencing the world!!!!
Just bought minnie mouse poncho from primark, very exciting!