December: December brings cooler days and clear water around Fort Jefferson, 70 miles west of Key West, without summer's heat or peak hurricane risk.
Permits and reservations
There is no entry reservation, but the park is reachable only by ferry, seaplane or your own boat.
Group campsite: Individual campsites are first come, first served and take no reservations. Parties of 10 or more must request the group campsite in advance with the park's group reservation form.
Ferry or seaplane: The park is 70 miles west of Key West and reachable only by the park ferry, a seaplane or your own boat. Reserve well ahead. Weather can cancel trips.