Sea temperature · NOAA OISST · 2011 to 2025
Key Largo water temperature by month
On average, the sea at Key Largo is coolest in January at 24.1 °C (75 °F) and warmest in August at 30.3 °C (87 °F).
What to wear. January to February: 3 mm full suit. March to May: 2 mm shorty or 1 mm full suit. June to October: rash guard or dive skin. November to December: 2 mm shorty or 1 mm full suit.
| Month | Average | Coolest to warmest year | Wetsuit |
|---|---|---|---|
| January | 24.1 °C 75 °F | 22.4 to 25.5 °C | 3 mm full suit |
| February | 24.4 °C 76 °F | 22.8 to 25.4 °C | 3 mm full suit |
| March | 25.0 °C 77 °F | 23.9 to 25.7 °C | 2 mm shorty or 1 mm full suit |
| April | 26.2 °C 79 °F | 25.5 to 27.4 °C | 2 mm shorty or 1 mm full suit |
| May | 27.6 °C 82 °F | 26.5 to 28.8 °C | 2 mm shorty or 1 mm full suit |
| June | 28.9 °C 84 °F | 27.9 to 29.7 °C | Rash guard or dive skin |
| July | 29.9 °C 86 °F | 28.8 to 31.5 °C | Rash guard or dive skin |
| August | 30.3 °C 87 °F | 28.9 to 31.2 °C | Rash guard or dive skin |
| September | 29.8 °C 86 °F | 28.8 to 30.4 °C | Rash guard or dive skin |
| October | 28.4 °C 83 °F | 27.6 to 28.9 °C | Rash guard or dive skin |
| November | 26.6 °C 80 °F | 25.7 to 27.3 °C | 2 mm shorty or 1 mm full suit |
| December | 25.5 °C 78 °F | 23.9 to 26.4 °C | 2 mm shorty or 1 mm full suit |
How we pick the wetsuit
We do not judge it month by month. Each month's average goes through the scuba column of Wetsuit thickness and temperature guide by Divernet, with scuba.com (updated , read ). The chart lists whole-degree bands with gaps between them, so a month that lands in a gap, say 27.6 °C, gets the thicker suit of the two. The bands that apply here:
- Over 28 °C: Rash guard or dive skin
- 25 to 27 °C: 2 mm shorty or 1 mm full suit
- 22 to 24 °C: 3 mm full suit
The chart is for an average diver. If you run cold, or plan three or four dives a day, go one step thicker. These are surface figures, and below a thermocline the water can be a few degrees cooler.
Questions
What is the water temperature in Key Largo?
On NOAA satellite averages for 2011 to 2025, the sea at Key Largo runs from 24.1 °C (75 °F) in January to 30.3 °C (87 °F) in August.
What wetsuit do I need for diving in Key Largo?
We apply the scuba column of Divernet's wetsuit chart, written with scuba.com, to each month's average. January to February: 3 mm full suit. March to May: 2 mm shorty or 1 mm full suit. June to October: rash guard or dive skin. November to December: 2 mm shorty or 1 mm full suit. Go one step thicker if you feel the cold or dive several times a day.
Source and date
Temperatures are NOAA's Daily Optimum Interpolation Sea Surface Temperature (OISST), version 2.1 (doi:10.25921/RE9P-PT57), published by NOAA National Centers for Environmental Information (NCEI), read as monthly means from NOAA's Physical Sciences Laboratory. We use the 0.25° ocean square at 25.125° N, 80.375° W, 8 km from the middle of the Key Largo dive sites. Each month averages that square over 15 years, 2011 to 2025. Retrieved from NOAA on .
Every destination side by side: water temperature by month. Download the numbers: conditions.csv · conditions.json. Back to Key Largo dive sites and stays.