Did the OP say when they were visiting?
We just went this past Monday and Tuesday, and the highs were 97 and 98 degrees, respectively. But here's the funny thing - - Monday was totally bearable, and I say that as someone who does NOT like hot weather. Yes, it was hot. Yes, it was sweaty. But we were able to take some air conditioning breaks, find shade here and there, and basically do alright. Nobody complained, and we had a great day.
Tuesday was a different story. We had EE, and were in the park at 8:00 for opening. By 8:15, we were dripping with sweat. The humidity was vastly different as compared to Monday. By the afternoon, we thought we might burst into flames as we walked in the direct sun. We got to the IASW line at around 2:00...no shade, and only one side open. 3 of our party of 8 decided to do the 20 min wait, but the rest of us bailed. We left early that day, as it really wasn't any fun for us. The other people in our group didn't have APs, so they sucked it up and stayed...but it was BRUTAL.