Grand Case Weather in September

September in Grand Case brings high temperatures, with daytime highs of 30°C (86°F) and nights around 27°C (81°F). Quite a bit of rainfall is expected, around 134 mm (5.3 in), so pack an umbrella.

Rainfall in Grand Case in September

Historically, approximately 19 days this month are expected to have rain, averaging 134 mm (5.3 in). Expect frequent rainfall this month, and not just light drizzle. When it rains, it tends to come down hard.

Temperature in Grand Case in September

In September, Grand Case sees high temperatures, with highs of 30°C (86°F). Nights drop to around 27°C (81°F). This kind of day-to-night contrast is typical for this time of year. With overnight lows of 27°C (81°F), nights stay very warm. Air conditioning makes a real difference if you're sensitive to heat. A cold shower before bed can also help you get to sleep more comfortably.

Sunshine in Grand Case in September

Expect sunny days throughout the month, with an estimated 232 hours of sunshine. This makes it a pleasant time to visit Grand Case.

Wind Speed in Grand Case in September

Wind speeds average 5 m/s (10 knots) during September. At this speed, gentle to moderate breezes make small trees sway and the wind creates whitecaps on water bodies. Daily variations range from moderate winds to stronger breezes, creating excellent conditions for sailing, kite flying and wind sports.

Average water temperature in September

With water at 29°C (84°F), conditions are warm and calm. Perfect for those who like tropical water temperatures, though it won't cool you down much.

September in Grand Case has its charm. However, if you're seeking pleasant, dry and sunny weather, our weather planner can help you explore other destinations in the world.

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For a detailed overview over the year and the best time to visit Saint Martin, check out our Grand Case's climate page.

Grand Case Temperature in September

Min Temperature 27°C (81°F)  

Max Temperature 30°C (86°F)  

Water Temperature 29°C (84°F) *  

Chance of Rain 62%  

Precipitation 134 mm (5.3 in)  

Rainy days 19 days  

Humidity 78% *  

Windspeed 5 m/s (10 knots) *  

Sunshine 232 hours *  

Percentage Sunshine 61% *  

* Data from: Sint Maarten, Sint Maarten (8 KM, 5 Miles).

Daily Historical Temperatures

50-year average (1976-2025)

Based on our historical records, temperatures in Grand Case typically stay consistent throughout September, with daily highs averaging around 30°C (86°F). Nights are warm, with lows around 27°C (81°F).

Average temperatures in September

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Historical weather for Grand Case in September

Browse day-by-day weather records for Grand Case spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.

Historical weather Temperatures Precipitation

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‹ January February March April May June July August September October November December ›

Grand Case historical weather extremes in September

Based on 35 years of weather observations (1990-2025), these are the most extreme conditions recorded in Grand Case.

• The warmest day in September was on September 3, 1992, with a maximum of 36°C (97°F).
• The lowest daytime temperature in September was 27°C (81°F), recorded on September 4, 2009.
• The lowest overnight temperature recorded in September was 21°C (70°F) (September 8, 2012).

What to Wear in Grand Case in September

Warm but pleasant conditions in Grand Case in September. Focus on lightweight, maybe with natural fabrics, cotton blend shirts, comfortable shorts, and breathable footwear. A light cover-up for sun protection is smart too. Expect heavy rainfall, so bring good rain protection and waterproof bags. With water temperatures around 29°C (84°F), swimming conditions are excellent. Pack your swimsuit, goggles, and maybe some water shoes. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.

What To Do in Grand Case in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

9/10

Cycling

7/10

Walking

7/10

Camping

7/10

Outdoor sports

7/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Saint Martin, check out our Grand Case's climate page.

More climate data for Grand Case

Temperature Rainfall Sunshine Humidity Wind Speed Water Temp

See the full Grand Case climate overview or explore weather in Saint Martin.