Agreed; downtown Charleston can be a sauna when it's like that. Likewise with the rest of the Charleston area. The entire lowcountry, for that matter.
Hey, on that sweatiest list, what's with Phoenix, Vegas, Tuscon, Corpus Christi, etc. being sweaty? They're supposed to have dry heat, right?
I definitely agree with Tampa and Orlando, though... yikes. If you've been to Didney Wurl in the summer, you know sweat. Also, about five years ago, I spent about a week near Eustis, Florida (just above Orlando) with about 20-25 buds and budettes from the U.S., Canada, and England who are members of an online jazz club I belong to and I can tell ya, that was the hottest, most humid place I've ever been. It was in August.
That's a big golfing area, and I don't know how anyone could play golf or tennis in that stuff. Unless it was at night, and even then, you'd be soaked. But daytime is oppressive for sure.
Most of us stayed at this motel near the club founder's house, and at 9:00 in the morning, you'd literally be covered with sweat just walking from your room to the lobby where the coffee was.