Marathon, Florida Keys weather in December
Temperature, sea and sunshine in December: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in December
Excellent
Best time to visit: March – May, July, November – December
What is the weather like in Marathon, Florida Keys in December?
In December, Marathon, Florida Keys is warm: daytime highs average 24 °C, and even at night it stays warm at around 22 °C. The sea averages 24.9 °C – pleasant for swimming. The sun shines for around 7 hours a day. Rain falls on about 5 days, adding up to 34 mm. The air is often humid and muggy. It is often windy, with gusts of around 29 km/h. All in all, December is an excellent month for a holiday in Marathon, Florida Keys.
December compared
How the weather changes from November to January. Tap a month to open it.
| NovemberNov | DecemberDec | JanuaryJan | |
|---|---|---|---|
| Score | 90 | 83 | 74 |
| Day | 25° | 24° | 22° |
| Night | 23° | 22° | 20° |
| Sea | 26° | 25° | 24° |
| Sun | 7 h | 7 h | 7 h |
| Rain days | 6 | 5 | 6 |
More details for December
- Daylight
- 10 h 37 min07:01 – 17:38
- UV index
- 5 · moderateclear sky, noon (estimate)All months
- Muggy days
- 19 daysdew point 18 °C or moreAll months
- Wind
- 29 km/haverage daily peakAll months
- Cloud cover
- 43 %on averageAll months
- Hot days
- 0 days30 °C or moreAll months
- Time zone
- UTC−5America/New_York
How the score comes together
- Temperatureweight 35 %78 %
- Seaweight 25 %100 %
- Sunshineweight 20 %62 %
- Few rainy daysweight 20 %91 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in December
- Swimwear
- Sunscreen
- Insect repellent
- Windproof jacket
Marathon, Florida Keys in December: quick answers
Is Marathon, Florida Keys hot in December?
Warm rather than hot: in December, daytime highs in Marathon, Florida Keys average 24 °C and nights cool to about 22 °C.
Can you swim in Marathon, Florida Keys in December?
Yes. In December the sea averages 24.9 °C – pleasant for swimming.
Does it rain much in Marathon, Florida Keys in December?
Rain falls on about 5 days, adding up to 34 mm.
Marathon, Florida Keys month by month
The whole year in Marathon, Florida KeysAll destinations: USAFlorida weather in DecemberWhere to go in DecemberSea temperature in December
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences