World sea water temperatures

Water temperature in Grand Isle (LA) in September

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Is it warm enough to swim in Grand Isle in September? Average water temperature in Grand Isle in September is 84°F and therefore suitable for comfortable swimming. The warmest sea in Grand Isle in September is 88.5°F, and the coldest is 77.9°F. Average high air temperature in Grand Isle in September is 87°F, and average low temperature is 73°F. To find out the sea temperature today and in the coming days, go to Current sea temperature in Grand Isle

Changes water temperature in Grand Isle in September 2025, 2024

To get an accurate forecast for the water temperature in Grand Isle for any chosen month, compare two years within a 10 year range using the chart below. In addition to the sea water temperature in Grand Isle, the selected years in the table also show the values of the maximum and minimum temperatures on each of the days of September.

You can choose any other years:

Year 1:   Year 2:


Day 2025 2024 Min Max
September 186.2°F84.6°F83.3°F88.5°F
September 284.6°F84.6°F81.7°F88°F
September 384.7°F85.3°F81.7°F87.6°F
September 485.5°F85.1°F81.7°F86.5°F
September 585.8°F85.1°F82.6°F87.8°F
September 6 85.1°F81°F87.8°F
September 7 84.9°F80.1°F87.8°F
September 8 82.6°F79.5°F87.8°F
September 9 82.6°F79.9°F88.3°F
September 10 82.9°F79.9°F88.2°F
September 11 83.1°F80.4°F88°F
September 12 81.7°F80.8°F88°F
September 13 82°F80.1°F87.8°F
September 14 82°F79.9°F87.8°F
September 15 83.3°F80.8°F87.4°F
Day 2025 2024 Min Max
September 16 84.9°F81.5°F88°F
September 17 85.3°F81.9°F86.9°F
September 18 86.5°F79°F87.4°F
September 19 86.2°F81°F87.4°F
September 20 86.2°F81.1°F87.3°F
September 21 85.8°F80.4°F87.6°F
September 22 85.3°F80.1°F87.1°F
September 23 85.5°F79.9°F87.1°F
September 24 86°F79.7°F87.3°F
September 25 85.6°F78.8°F86.5°F
September 26 85.1°F77.9°F86.4°F
September 27 84°F78.1°F85.8°F
September 28 83.5°F78.3°F86°F
September 29 82.8°F78.3°F85.1°F
September 30 82.4°F78.8°F84.4°F
Grand Isle water temp chart in September

Average water temperature in Grand Isle in September over a decade

20152016201720182019
83.1°F85.1°F83.1°F85.1°F85.3°F
20202021202220232024
83.7°F82.6°F85.5°F86.4°F84.4°F

Grand Isle sea state in September

Chart comparing the height of waves in Grand Isle in September over the past years. The red line indicates the height of the waves when swimming in the sea is prohibited. To view the current sea conditions, click on the graph.

Waves height in Grand Isle in September

Weather and climate in Grand Isle in September

This data display average monthly climate indicators in Grand Isle in September based on our historical weather readings over a period of ten years. In addition to temperature, we include data on the number of rainy and sunny days so you can have all the information about your destination before your trip

  • Average HIGH temperature87°F
  • Average LOW temperature73°F
  • Average rainfall170mm/6.7''

Grand Isle water temperature during other months:

You can also view information about water temperature for other months by clicking on the month button below

Where is the warm sea water in September?

Want to know where the water temperature in September is good for swimming? Select the continent of interest, the day of the month and the required water temperature

Region
Date (day and month)
Water temperature: min 60°F
 Average temperature  Maximum temperature

Temperature in neighboring cities

The nearest locations with the average water temperature in September. In addition, the maximum and minimum water temperatures for that month, recorded over the last decade, are shown

AvrMinMax
Buras83.8°F77.7°F88.2°F
Cocodrie84°F78.1°F88.3°F
Boothville83.3°F76.8°F87.6°F
Shell Beach83.1°F76.8°F88.2°F
Venice83.5°F77.4°F87.4°F
Mandeville82.8°F75°F87.8°F
Chandeleur Islands83.8°F78.3°F87.6°F
Waveland82.9°F76.6°F88.2°F
Bay Saint Louis82.9°F76.5°F88.2°F
Gulfport83.1°F76.1°F87.8°F

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[1] - The "Blue Flag" is awarded to beaches which fulfill a number of criteria, including: the quality of the bathing water, which must be in accordance with the relevant European Union Directive environmental education and information and beach area management and safety.

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Our report for Grand Isle is compiled using satellite data together with in-situ observations to get the most reliable daily data of sea surface temperatures, surf forecasts, current temperatures and weather forecasts.

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