Month-specific sea-surface temperature · USA

Crystal River Sea Temperature in December

17.2°C

63.0°F

In December, sea-surface temperature near Crystal River has a historical monthly average of 17.2°C. This is not the reading for any particular holiday date.

Across 2023–2025, the lowest and highest yearly December monthly means were 16.2–18.3°C. These are not daily extremes.

Previous month

November · 21.8°C

Change into December: -4.6°C

Next month

January · 14.4°C

Change into next month: -2.8°C

Can you swim or snorkel in Crystal River in December?

At 17.2°C our temperature-only guide describes the water as cold 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?

Use a full 3-5 mm wetsuit and keep the session within your cold-water experience.

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.

Compare nearby coasts with their own evidence

Coast	Morning	Afternoon	Period
Key Largo	58%	62%	Dec 2025
Dry Tortugas	26%	32%	Dec 2025
Bahia Honda	44%	45%	Dec 2025
Looe Key	41%	43%	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.

Crystal River Sea Temperature: All 12 Months

Choose a month for available historical evidence, month comparisons and swim guidance. Missing history is clearly marked and never presented as a long-term normal.

January 14.4°C February 17.2°C March 21.0°C April 24.0°C May 27.5°C June 29.8°C July 31.4°C August 31.5°C September 29.7°C October 25.7°C November 21.8°C December 17.2°C

Data source and limitations

Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature; 2023–2025. Marine model grid near 28.90, -82.59. 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.