Hi,
I live about 65 miles due west of WDW. I'm an AP and DVC member. End of May early June is normally blistering hot. Hate to say it but it is. Summer afternoon T-storms usually haven't kicked in to full gear so it's hotter than most people expect. I'd bring both ponchos and lots of sunscreen.
This March has been extremely hot for us so I think we maybe in for a very hot summer. We are currently experiencing May temperatures in March. Not normal. Enjoy your trip.