I live in Florida, too (West Palm). From June through September, it's really hit or miss whether you can ride after 5:00, since storms pop up pretty much every night and don't settle down until the sun sets. I will run after 6:00 or 7:00, but not ride or ocean swim.
If I ride, I will do so in the morning to midday. Of course, first light is best, but if you live in an area where this is heavy morning commuter traffic, that can be a problem, too. I will wait until traffic dies down, usually after 8:30. I use a camelbak with water. I'll also bring a water bottle with Heed or something similar, plus electrolyte capsules. My camelbak holds lots of stuff, so I'll bring a snack, my cell phone, and some money just in case. The thing that makes it easier to ride in the heat rather than run in the heat is that the faster you go, the more wind you generate, and the cooler you feel.
So, if all else fails, ride faster!
"God gave you your body as a gift, so you should take care of it." - My Mom