It was 85 last week, but the great thing about Disney, is they have air-condition everywhere. And if you are standing in lines, they have fans blowing on you.
Epcot is hot though, they have more concrete area's (open area's), just take your time, find shade tree's.
We went 2 years ago in June and it was in the 100's. We really didn't even notice until you walk to your next destination to get in line, then air condition and fans again.