Late winter is rainy season, I am told, but even then it is rare for rain to set in all day. Winter also comes with rougher surf, especially on the north shores, for some reason. More of the diving, snorkeling, and boat tours get cancelled.
The flip side is that if you get a somewhat calm sea winter day, that is the peak time for seeing whales and dolphins.
My daughter is at UH, on Oahu, in Honolulu. She does outdoor stuff like hiking all year long, though summers are in her opinion a bit humid. Nothing like south FL though. 80-85 and humid beats 90 and humid any time.