As the summer heat starts to cool down across the United States, Marathon maintains an average high temperature of 88° F (31° C). The water temperature may be around the mid-80s (30° C), but the sea is still perfect for ocean activities such as swimming, snorkeling or diving. September often brings afternoon thunder storms, but the rain rarely sticks around long enough to spoil an entire day.

You may be concerned about the Atlantic hurricane season as you plan your vacation in the Keys. Hurricanes may affect the Atlantic and Gulf coasts of the United States from June 1st through November 30th. Traditionally August 15th through October 15th presents the highest potential for storms. Tranquility Bay Resort offers a hurricane clause to protect our guests during this period so please inquire within our call center.