Measurements:
°C
°F
CURRENT WEATHER
08:40
Grand Isle
86°F
S 8 mph
Feels like: 94°F
Precip: 31%
World Resorts USA Grand Isle Weather

7 Day Weather Forecast

09.15
tue
DAY
88°F
W 4 mph
precip
5%
NIGHT
88°F
W 9 mph
precip
17%
09.16
wed
DAY
90°F
W 14 mph
precip
28%
NIGHT
88°F
W 17 mph
precip
14%
09.17
thu
DAY
90°F
W 17 mph
precip
12%
NIGHT
86°F
W 10 mph
precip
3%
09.18
fri
DAY
88°F
SW 10 mph
precip
11%
NIGHT
86°F
NW 7 mph
precip
14%
09.19
sat
DAY
86°F
W 5 mph
precip
3%
NIGHT
86°F
NW 13 mph
precip
14%
09.20
sun
DAY
86°F
N 7 mph
precip
42%
NIGHT
86°F
N 12 mph
precip
13%
09.21
mon
DAY
88°F
N 10 mph
precip
27%
NIGHT
86°F
N 11 mph
precip
9%

Grand Isle Sea Water Temperature in September, °F

Select Year: 2026 2025 2024

The average sea surface temperature in September 2026 for Grand Isle was 30.6°F. The maximum and minimum values were 30.1°F and 31.3°F respectively.

Grand Isle on the Weather Map

Best Time to Visit Grand Isle
The most sunny months:
October 18 days
September 15 days
November 14 days
The most warm months:
August 89.7 °F
July 89.3 °F
June 87.5 °F
Warmest sea temperature:
August 92.2 °F
July 91.3 °F
June 89.0 °F
The most cold months:
January 59.3 °F
February 62.0 °F
December 63.8 °F
The most rainy months:
August 4 days
July 4 days
September 4 days
The most windy months:
January 13 mph
April 13 mph
March 12 mph
more details