About 10 years ago I fished Key West and out to the Marquesses Keys during late June. The temperature rarely got above 85 during the day, and at night, we fished the Key West Harbor area and temperatures ranged about 75 to 80. However, the humidity was not really that bad at all. On the way home we stopped near Fort Myers, fished Boca Grande Cut and it felt like we were fishing in a sauna.
Back home in Maryland's portion of Chesapeake Bay, July and August can be brutal with lots of days where the temperature and humidity readings are just about the same--95/95. Conditions were much better in Key West during the same time frame.