The manatee season runs from November through March, peaking in December and January. Cooler Gulf water temperatures push the manatees into the warm springs in the greatest numbers. If swimming with manatees is your reason for coming, January is the best month — expect 50 to 200 manatees in Kings Bay on a typical winter morning.
From April to October, the manatees disperse into the Gulf and nearby rivers. The springs remain beautiful and swimmable, and summer brings scalloping season (July through September), when locals wade the seagrass flats harvesting bay scallops. Summer is also hurricane season — Florida's Gulf Coast is exposed, so check the forecast if you're visiting between August and October.
Winters are mild — highs in the 60s°F (15–20°C) — and the weather for the manatee season is usually pleasant with clear skies. Spring and fall are the quietest periods and perfectly good for kayaking and fishing.