The best time to visit Big Coppitt Key for pleasant weather and fewer crowds is during the shoulder seasons, specifically from April to May and again from October to November.
During these months, you'll experience comfortable temperatures, typically ranging from the mid-70s to low 80s Fahrenheit, which is ideal for enjoying outdoor activities like fishing, kayaking, or simply relaxing by the water. The humidity is also lower than in the peak summer months, making for a more enjoyable experience. You'll find that hotels and attractions are generally less crowded, and you might even find better deals on accommodations compared to the busiest winter season.
For travelers who enjoy water sports and don't mind warmer temperatures, the late spring (April-May) offers excellent conditions. The waters are warming up, making swimming, snorkeling, and diving particularly inviting. This period is also before the peak hurricane season, offering a more worry-free travel experience.
If your priority is avoiding the busiest tourist times and enjoying mild weather, the fall (October-November) is an excellent choice. The summer heat has begun to subside, and the crowds from the winter high season haven't yet arrived.