Central Florida this time of year is plenty hot and humid. I check weather.com for the rain chance but really never look at the temperature. I know it's going to be hot already... Usually the rains hit for a while between 3 and 5 PM. Sometimes riding home in the rain is actually quite refreshing. Once it's summer here I just hope for enough wind from riding to keep me cool. All that aside I usually don't ride for over an hour, but have done two hours on weekends in this weather.
About all you can do is drink plenty of water and not push too hard. I'm also a fan of the Polar bottles. They make the difference between slightly cool and blood warm after a half hour.