Like others have said, the humidty makes a massive difference. Last year I went to Jamaica on vacation, on the day we left Jamaica it was 86 degrees with 80% humidty, it felt soooo hot. When I got back home to California it was 93 degrees, but 22% humidty. The result was, it felt much, much, much cooler to me to be in the 93 degree heat than it did in the 86 degree heat the previous day in Jamaica.
Hottest I've been in tempwise is probably about 117, but that was like 20% humidty. But, 99 with 75% humidty that I felt in Mashalltown, Iowa one time was the worst.