the springs on the eastern side of the panhandle are 71-72 degrees year round. I’m from NJ (living in FL now) and have done 3-3.5 hour dives in the springs in a wetsuit and I’m fine. Hardly cold! :)
the western/northern side of the panhandle the springs are closer to 68 degrees. In some places where you have intrusion from a river or in a pond, you will find water temps in the 50s in the winter.
In the winter, even the ocean drops to 70-ish near the surface so be prepared.
Ocean diving: Jupiter, BHB, and Pompano.
Fresh water: Ginnie Springs, Jackson Blue Spring, and Madison Blue Spring.
Have fun, Steve