Low 90s is the "norm" for mid-day. Low 70s for very early or very late.
But it can vary up or down as much as about 4 degrees from day to day, so best be prepared for anything.
But in addition to the heat, crowds will high in June. This is a much bigger incentive for me to go early or late than the temperature. If you decide to be there mid-day, there's usually somewhere to duck into air conditioning. But long lines at the most popular attractions are not avoidable mid-day (except for judicious use of FP) and it's difficult to navigate around, or get food quickly.
So go early and late to enjoy the most popular attractions, and save the AC'd attractions and shops, and of course back to the resort and the pool, for mid-day.