Grand Isle Weather: September
 |
Average Day Temperature: | 85.9°F |
|
Average Night Temperature: | 83.3°F |
|
Sea Water Temperature: | 88.6°F |
|
Number of Sunny Days: | 15 days |
| Sunshine Hours: | 11.9 - 12.7 hours | |
|
Number of Rainy Days: | 4 days |
| Precipitation Totals: | 2.2 in | |
| detailed information | ||
forecast
| Grand Isle |
Temperature
| Grand Isle |
Air Temperature in September, °F
The highest day temperature in September 2025 was 89°F. The lowest night temperature was 83°F. The average values for day and night temperatures during September were 86.8°F и 84.4°F respectivly.
Grand Isle Water Sea Temperature in September, °F
The average sea surface temperature in September 2025 for Grand Isle was 89.1°F. The maximum and minimum values were 87.6°F and 92.4°F respectively.
Most of the days in September are sunny but you can also expect cloudy and gloomy days.
Precipitation Totals in September, in
Precipitation total in September for Grand Isle is 2.2 in. It makes september one of the most rainy months of the year.
The average wind speed in September is 10.2 mph. It makes September one of the most windless months of the year for Grand Isle.
We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Grand Isle in September is 7.7 hours.
Grand Isle on the Weather Map
| Boston |  |
+96 |
| Chicago | |
+86 |
| Hawaii |  |
+82 |
| Houston |  |
+80 |
| Las Vegas |  |
+118 |
| Los Angeles | |
+100 |
| Maui | |
+78 |
| Miami | |
+96 |
| Myrtle Beach | |
+90 |
| New York | |
+104 |
| San Diego | |
+94 |
| San Francisco | |
+82 |
| Santa Monica | |
+82 |
| Sarasota | |
+96 |
| Tampa | |
+98 |
| 1800 |  |
90°F | N 11 mph |
| 2100 |  |
90°F | S 14 mph |
| 0000 | |
90°F | W 4 mph |
| 0300 |  |
86°F | N 9 mph |
| 0600 | |
88°F | N 10 mph |
| 0900 |  |
88°F | N 5 mph |
| 1200 | |
88°F | NW 7 mph |
| 1500 | |
90°F | N 9 mph |