Climate may be the Florida Keys' greatest natural resource. It affects many aspects of our lives whether we are residents or seasonal visitors. Climate affects the tourism and fishing industries, recreational diving and boating activities, and the unique aquatic and terrestrial environments found in the Keys.

The tropical maritime climate of the Florida Keys is attributable to its geographic location. Extending in a gentle southwesterly arc off the southern tip of the Florida peninsula, the Keys are bathed in the warm waters of the Atlantic Ocean and the Gulf of Mexico. The Gulf Stream, a warm water current flowing around the western tip of Cuba, through the Straits of Florida, and northward along the lower east coast, also exerts its warming influence on the Keys.

The maritime influence of the surrounding oceans regulates the climate like a hot water bottle, tempering the tropical summer heat and the invading continental cold fronts of winter. Temperature extremes in the Keys are moderated by the air’s contact with the surrounding waters. Water has one of the highest heat capacities of all known substances, which means that it heats more slowly than land and retains heat longer. Consequently, the weather may vary from day to day, but the long-term climate remains moderate and mild, characterized by a long, warm summer followed by a mild, dry winter.