Complex sentence: On the Florida peninsula, the humid subtropical climate gradually changes to the tropical climate of south Florida and the Florida Keys below Stuart, Fl on the Atlantic coast and near Fort Myers, Fl on the Gulf of Mexico side.
Split into simpler sentences: On the Florida peninsula, the humid subtropical climate gradually changes to the tropical climate of south Florida and the Florida Keys. The rough dividing line between the subtropical and tropical climates are Stuart, Fl on the Atlantic coast and near Fort Myers, Fl on the Gulf of Mexico side.