Big Bend
Cedar Key Water Temperature
Old Florida island town on the Nature Coast's outer keys.
That is about 2°F warmer than average for this time of year, and holding steady over the last two weeks. The September average here is 84°F.
Updated Monday, September 21 — sea-surface temperature modeled for Cedar Key by Open-Meteo.
For swimming
Very warm
Bath-warm. Pleasant, though it stops being much relief from the heat of the day.
For fishing
Hot — fish the edges of the day
Early and late is the play. Through the middle of the day fish drop into deeper channels and passes where there's moving water and more oxygen.
The last two weeks
Daily average sea-surface temperature, °F.
Cedar Key water temperature by month
Averaged from 3 years of daily sea-surface temperature (2023–2025). The range column is the coolest and warmest daily average recorded in that month over the period — a guide to how much any given year can differ, not a record high and low.
| Month | Average | Range | Swimming |
|---|---|---|---|
| January | 56°F | 50–62°F | Cold |
| February | 62°F | 57–70°F | Bracing |
| March | 68°F | 62–74°F | Cool but comfortable |
| April | 74°F | 70–79°F | Cool but comfortable |
| May | 81°F | 74–87°F | Warm |
| June | 85°F | 79–89°F | Very warm |
| July | 88°F | 86–90°F | Bath water |
| August | 88°F | 84–91°F | Bath water |
| Septembernow | 84°F | 81–88°F | Very warm |
| October | 77°F | 71–84°F | Warm |
| November | 70°F | 64–78°F | Cool but comfortable |
| December | 61°F | 57–66°F | Bracing |
Warmest on average in July at 88°F; coolest in January at 56°F.
The water at Cedar Key
Cedar Key is a working island town of clapboard buildings, clam farms, and no chain stores, sitting at the edge of a scatter of outer keys and oyster bars. Redfish and trout work the grass and the bars, sheepshead pile onto the dock pilings and rock in winter, and tarpon roll through the outside channels in summer. It's one of the few places on this coast with a NOAA water-temp sensor right in town, which makes reading the season easy.
the Gulf, the back bays & the outer keys
What moves the water temperature here
The Gulf shelf off this coast is shallow, which is why the water swings so much more between summer and winter than open ocean at the same latitude does. Shallow water heats fast and gives that heat up fast: a single strong winter cold front can pull the inshore bays several degrees down in a couple of days, while the beaches a mile offshore barely move. Wind direction matters too — a sustained offshore breeze can pull cooler water up from below and drop the beach temperature noticeably in a morning.
Inshore bays, canals and flats run warmer than the beach through the summer and colder through the winter, for the same reason. The reading above is for the open water at Cedar Key; expect the back bays to be a few degrees either side of it depending on the season.
Common questions
- What is the water temperature at Cedar Key right now?
- The water at Cedar Key is currently about 86°F (30°C). The September average here is 84°F.
- Is the water warm enough to swim at Cedar Key in September?
- September averages 84°F at Cedar Key, which most people would call very warm. Bath-warm. Pleasant, though it stops being much relief from the heat of the day.
- When is the water warmest at Cedar Key?
- July is the warmest month on average at 88°F, and January the coolest at 56°F. 6 months of the year average 75°F or above.
- Why does the water temperature change so quickly here?
- The Gulf shelf off this coast is shallow, so it heats and cools far faster than deep open ocean. A strong winter cold front can pull the inshore water down several degrees in a couple of days, and a sustained offshore wind can drop beach temperatures in a single morning by pulling cooler water up from below.