Sarasota Coast
Longboat Key Water Temperature
Longboat Pass, New Pass, and a beach on the tarpon migration route.
That is about 4°F warmer than average for this time of year, and cooling over the last two weeks. The October average here is 80°F.
Updated Saturday, October 3 — sea-surface temperature modeled for Longboat Key by Open-Meteo.
Out in the open Gulf, NOAA buoy 42013 — 23 miles offshore — is reading 86°F. Deep water offshore runs cooler than the shallows in summer and warmer in winter, so it won't match the beach.
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.
Longboat 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 | 63°F | 55–68°F | Bracing |
| February | 67°F | 61–74°F | Bracing |
| March | 71°F | 66–77°F | Cool but comfortable |
| April | 76°F | 73–80°F | Warm |
| May | 82°F | 77–87°F | Very warm |
| June | 86°F | 82–88°F | Very warm |
| July | 89°F | 86–90°F | Bath water |
| August | 89°F | 85–92°F | Bath water |
| September | 86°F | 84–88°F | Very warm |
| Octobernow | 80°F | 75–86°F | Warm |
| November | 73°F | 67–79°F | Cool but comfortable |
| December | 67°F | 63–72°F | Bracing |
Warmest on average in July at 89°F; coolest in January at 63°F.
The water at Longboat Key
Longboat Key is eleven miles of barrier island with a pass at each end, and those two cuts — Longboat Pass to the north and New Pass to the south — are where the fishing concentrates. Snook stack on the bridge and jetty structure with the current, and the sand at the north end near Greer Island fishes well for reds and trout on the right water. In late spring and early summer, tarpon move down the beach in strings within easy sight of the sand, part of the same migration that makes Boca Grande famous. The beach itself is quiet and low-rise by Florida standards, good for a long walk or a paddle inside the bay. Behind the island, Sarasota Bay's grass flats hold trout year-round.
Sarasota Bay & Longboat Pass
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 Longboat 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 Longboat Key right now?
- The water at Longboat Key is currently about 84°F (29°C). The October average here is 80°F.
- Is the water warm enough to swim at Longboat Key in October?
- October averages 80°F at Longboat Key, which most people would call warm. About as good as it gets — warm enough to stay in for hours without getting chilled.
- When is the water warmest at Longboat Key?
- July is the warmest month on average at 89°F, and January the coolest at 63°F. 7 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.