Month-specific sea-surface temperature · USA
Dry Tortugas Sea Temperature in December
24.9°C
76.8°F
In December, sea-surface temperature near Dry Tortugas has a historical monthly average of 24.9°C. This is not the reading for any particular holiday date.
Across 2023–2025, the lowest and highest yearly December monthly means were 24.7–25.1°C. These are not daily extremes.
Previous month
November · 26.7°C
Change into December: -1.8°C
Next month
January · 23.2°C
Change into next month: -1.7°C
Can you swim or snorkel in Dry Tortugas in December?
At 24.9°C our temperature-only guide describes the water as mild water. Comfort depends on your cold tolerance, immersion time and wind. A historical average cannot determine whether conditions are safe on any given day.
Do you need a wetsuit?
A rash guard is useful; cold-sensitive snorkelers may prefer a shorty wetsuit.
Which beach should you choose?
Look for a beach sheltered from the actual forecast waves and wind on your visit. Exposure, currents and entry conditions vary even where water temperatures are similar. Follow local warnings.
Check the current waves, wind and snorkeling forecast →
A live forecast does not predict a future December. Check again close to your trip.
Waves and wind: recorded-model conditions for December
These figures come from a separately modelled, date-specific wind/wave backfill, not the NOAA SST series. A single observed season is not a climatological likelihood or a guarantee of safe conditions.
Morning calm hours
26%
Afternoon calm hours
32%
Historical coverage
December 2025
31 valid days
Compare nearby coasts with their own evidence
| Coast | Morning | Afternoon | Period |
|---|---|---|---|
| Looe Key | 41% | 43% | Dec 2025 |
| Bahia Honda | 44% | 45% | Dec 2025 |
| Key Largo | 58% | 62% | Dec 2025 |
A “calm hour” meets fixed modelled wave/wind thresholds; neither visibility nor local currents, entry conditions or actual beach safety is measured here. Periods may differ by coast.
Nearby places in December
Comparable historical averages from independent marine grid cells. Warmer water does not imply safe snorkeling.
- Looe Key 25.6°C
Data source and limitations
Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature; 2023–2025. Marine model grid near 24.63, -82.87. Based on 3 yearly monthly means and 2232 recorded samples. Source methodology.
Modelled sea-surface temperatures do not establish underwater visibility, wildlife, calm currents or safe entry.