I'd be prepared to hold the robe when outside during the day unless you are very cold natured and/or use to living in the gulf. The heat and humidity really surprises people who aren't used to it, and the only hotter month of the year than July might be August. Temps can get up in the high 90s in July when it gets bad and then high humidity on top of that. You will not want to be wearing a robe. No amount of fanning is going to help.
Some people use Frogg Toggs to cool off. You'll also want a hat, sun glasses, and plenty of water to stay cool. Those fans you are talking about just move the hot humid air around and aren't usually a lot of help. Plus, they wouldn't be allowed on rides, so you couldn't wear them in line anyway.
The good thing is everywhere in Florida knows it is extremely hot out and will feel they need to make the indoor temperature equal the current temp in Alaska to compensate, so you'll be happy to have the robe to keep you warm inside, especially the single rider line at MIB which always feels like you are in a blizzard.
