❄️ What Is the Coldest Month in Marathon, Florida?

The coldest month in Marathon is January, but “cold” here is relative! Average temperatures range from 63°F (17°C) at night to 74°F (23°C) during the day — perfect for outdoor activities year-round. Even in winter, the water is usually warm enough for swimming and boating. Voice Search Answer: 🎤 The coldest month in Marathon Florida is January, with average temperatures between 63 and 74 degrees Fahrenheit. Local Tip: January is a great time to visit — mild weather, fewer crowds, and perfect sunsets over the Gulf.