Winter is the obvious season — December through March bring warm afternoons (in the 70s Fahrenheit), cool nights, and low humidity. This is also the kumquat harvest, with the Kumquat Festival the last weekend of January.
Summer is hot, humid, and prone to afternoon thunderstorms. Manageable if you plan an early-morning walk and retreat indoors for the afternoon, but most travellers prefer the cooler half of the year.
The Pioneer Florida Day weekend over Labor Day is another reliable draw if you are timing a visit around a festival.