September is a popular month to ask about Siesta Key because conditions can shift week to week along this coast. Expect the water near 29.0°C, with daily variation from wind, tides and recent storms. We refresh the live value from Open-Meteo Marine every hour, so the headline above always reflects the current state of the Gulf of Mexico.
Siesta Key sea temperature in September — averages 29.0°C
The sea at Siesta Key in United States averages 29.0°C during September, based on long-run climatology for the Gulf of Mexico. Use the live reading below for today's actual water and the monthly grid to compare with the rest of the year.
Average sea · September
29.0°C
tropical · Excellent
Live water now
…
Recommended wetsuit
No wetsuit
At 29.0°C the water is warm enough to swim and surf in just a swimsuit or boardshorts.
Monthly comparison
Yes — ideal swimming weather · Siesta Key
Can you swim at Siesta Key in June? — 29.0°C water29.0°CCan you swim at Siesta Key in July? — 30.0°C water30.0°CCan you swim at Siesta Key in August? — 30.0°C water30.0°CCan you swim at Siesta Key in September? — 29.0°C water29.0°CCan you swim at Siesta Key in October? — 27.0°C water27.0°CCan you swim at Siesta Key in November? — 23.0°C water23.0°C
Frequently asked questions
What is the average sea temperature at Siesta Key in September?
Siesta Key averages 29.0°C in September, based on long-run climatology for the Gulf of Mexico.
Is the sea warm enough to swim at Siesta Key in September?
Yes, most swimmers find 29.0°C comfortable for unrestricted swimming.
Do I need a wetsuit at Siesta Key in September?
No wetsuit needed.