Key Largo Water Temperature
Updated Fri 05:55 (America/New_York)
USA · Forecast updated Sep 25, 2026, 05:55 UTC
Current Sea Temperature
29.7°C
85.5°F
Very warm water
Valid Sep 25, 2026, 05:55 (America/New_York). Source: stored Open-Meteo marine forecast. Temperature is not a safety rating or snorkel score.
Versus this month's average
1.0°C below
The typical September average is 30.7°C (87.3°F) from the historical baseline.
Recent trend
Cooling by 0.8°C
Seven-day average: 30.4°C, versus 31.2°C in the prior seven days.
What to wear
Very warm water
Swimwear is usually enough; a rash guard adds sun protection.
Cold tolerance varies. Wind, session length, sunshine, and exertion also affect comfort; temperature alone does not describe sea conditions or replace the snorkel forecast.
Key Largo is the northern gateway to the Florida Keys reef tract, including John Pennekamp Coral Reef State Park. Use this page for water temperature, then check the live forecast for wind, waves and the day's snorkel score. Temperature alone is not a safety rating.
Typical Sea Temperature Over the Year
In the historical baseline for Key Largo, typical monthly averages range from about 22.2°C (72.0°F) in January to 31.4°C (88.5°F) in August.
Over the past 30 days, the average sea temperature in Key Largo has been 31.2°C.
Historical baseline (full year)
Northern Hemisphere. Summer is generally June–August; winter is December–February.
Typical monthly sea-surface temperature near Key Largo, calculated from hourly observations for 2023–2025. This is not this site's forecast archive.
| Month | Typical range | Average |
|---|---|---|
| January | 21.2–22.8°C | 22.2°C / 72.0°F |
| February | 21.9–25.2°C | 23.6°C / 74.5°F |
| March | 24.2–25.8°C | 25.2°C / 77.4°F |
| April | 25.5–27.3°C | 26.2°C / 79.2°F |
| May | 28.5–29.6°C | 28.9°C / 84.0°F |
| June | 29.6–30.7°C | 30.1°C / 86.2°F |
| July | 30.2–32.4°C | 31.2°C / 88.2°F |
| August | 30.8–31.8°C | 31.4°C / 88.5°F |
| September | 30.4–30.9°C | 30.7°C / 87.3°F |
| October | 28.0–28.4°C | 28.3°C / 82.9°F |
| November | 25.5–25.9°C | 25.7°C / 78.3°F |
| December | 23.1–24.8°C | 23.7°C / 74.7°F |
Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature dataset. Nearest sea grid cell (25.13, -80.46). Each month is the mean of yearly monthly means; the range is the lowest and highest of those yearly monthly means. Open-Meteo methodology.
Water temperature by month
Each month uses the 2023–2025 baseline. The range is the lowest and highest yearly monthly mean, not an hourly extreme.
Key Largo in January
Typical January water temperature near Key Largo is 22.2°C (72.0°F), with yearly monthly means from 21.2–22.8°C.
Key Largo in February
Typical February water temperature near Key Largo is 23.6°C (74.5°F), with yearly monthly means from 21.9–25.2°C.
Key Largo in March
Typical March water temperature near Key Largo is 25.2°C (77.4°F), with yearly monthly means from 24.2–25.8°C.
Key Largo in April
Typical April water temperature near Key Largo is 26.2°C (79.2°F), with yearly monthly means from 25.5–27.3°C.
Key Largo in May
Typical May water temperature near Key Largo is 28.9°C (84.0°F), with yearly monthly means from 28.5–29.6°C.
Key Largo in June
Typical June water temperature near Key Largo is 30.1°C (86.2°F), with yearly monthly means from 29.6–30.7°C.
Key Largo in July
Typical July water temperature near Key Largo is 31.2°C (88.2°F), with yearly monthly means from 30.2–32.4°C.
Key Largo in August
Typical August water temperature near Key Largo is 31.4°C (88.5°F), with yearly monthly means from 30.8–31.8°C.
Key Largo in September
Typical September water temperature near Key Largo is 30.7°C (87.3°F), with yearly monthly means from 30.4–30.9°C.
Key Largo in October
Typical October water temperature near Key Largo is 28.3°C (82.9°F), with yearly monthly means from 28.0–28.4°C.
Key Largo in November
Typical November water temperature near Key Largo is 25.7°C (78.3°F), with yearly monthly means from 25.5–25.9°C.
Key Largo in December
Typical December water temperature near Key Largo is 23.7°C (74.7°F), with yearly monthly means from 23.1–24.8°C.
Forecast archive (growing)
These values come from hourly forecasts SnorkelForecast has stored. They cover only months with records and do not replace the historical baseline.
| Month | Min | Average | Max |
|---|---|---|---|
| June | 28.5°C / 83.3°F | 30.5°C / 86.9°F | 31.9°C / 89.4°F |
| July | 30.6°C / 87.1°F | 31.3°C / 88.3°F | 32.1°C / 89.8°F |
| August | 30.8°C / 87.4°F | 31.7°C / 89.1°F | 32.6°C / 90.7°F |
| September | 29.7°C / 85.5°F | 31.0°C / 87.7°F | 32.0°C / 89.6°F |
Partial coverage: 4 calendar months with records. Profile calculated from 2798 hourly forecast records across 4 monthly periods. This is a growing archive, not a long-term climate normal.
About the water at Key Largo
Gateway to John Pennekamp park and the shallow Florida Keys reef tract.
- Area
- Florida
Key Largo Water Temperature: Common Questions
What is the water temperature in Key Largo today?
The current sea surface temperature near Key Largo is 29.7°C (85.5°F). Over the last 30 days, the average has been 31.2°C.
When is the water warmest in Key Largo?
The water is typically warmest in August, at around 31.4°C (88.5°F) in the 2023–2025 historical baseline.
When is the water coldest in Key Largo?
The water is typically coldest in January, at around 22.2°C (72.0°F) in the same historical baseline.
Can you swim in Key Largo today?
At 29.7°C, the water is usually comfortable for swimming and snorkeling.
Full Snorkeling Forecast
See how today's sea temperature, wave height, wind, and tides combine into a detailed snorkeling score for Key Largo.
View Snorkel Forecast →