Marathon, Florida Keys weather in May
Temperature, sea and sunshine in May: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in May
Excellent
Best time to visit: March – May, July, November – December
What is the weather like in Marathon, Florida Keys in May?
In May, Marathon, Florida Keys is warm: daytime highs average 27 °C, and even at night it stays warm at around 25 °C. The sea averages 27.3 °C – lovely and warm for swimming. With around 9 hours of sunshine a day, there is plenty of sun. Rain falls on about 8 days, adding up to 67 mm. The air is often humid and muggy. All in all, May is an excellent month for a holiday in Marathon, Florida Keys.
May compared
How the weather changes from April to June. Tap a month to open it.
More details for May
- Daylight
- 13 h 19 min06:41 – 20:00
- UV index
- 12 · extremeclear sky, noon (estimate)All months
- Muggy days
- 29 daysdew point 18 °C or moreAll months
- Wind
- 25 km/haverage daily peakAll months
- Cloud cover
- 39 %on averageAll months
- Hot days
- 0 days30 °C or moreAll months
- Time zone
- UTC−4America/New_York
How the score comes together
- Temperatureweight 35 %100 %
- Seaweight 25 %100 %
- Sunshineweight 20 %100 %
- Few rainy daysweight 20 %71 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in May
- Swimwear
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- Insect repellent
- Rain jacket or umbrella
Marathon, Florida Keys in May: quick answers
Is Marathon, Florida Keys hot in May?
Warm rather than hot: in May, daytime highs in Marathon, Florida Keys average 27 °C and nights cool to about 25 °C.
Can you swim in Marathon, Florida Keys in May?
Yes. In May the sea averages 27.3 °C – lovely and warm for swimming.
Does it rain much in Marathon, Florida Keys in May?
Rain falls on about 8 days, adding up to 67 mm.
Marathon, Florida Keys month by month
The whole year in Marathon, Florida KeysAll destinations: USAFlorida weather in MayWhere to go in MaySea temperature in May
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