Most seem to do okay with heat...I've heard a couple people say they've had issues with wyandottes. And black chickens especially will need constant access to shade so they can escape the sunlight as needed.
In general, the bigger the comb and wattles, the better for hot weather. And fatter/fluffier chickens usually don't do as well as slimmer breeds. That said, brahmas do fine in heat and they are pretty floofy AND don't have the largest combs.
Our cuckoo marans have done well. Easter eggers are also usually very hardy. I've also heard australorps do well.
You don't need to worry about cold with chickens in Florida...20 degrees will not phase them as long as they are in a dry shelter.