Grand Case Beach sargassum & beach forecast
Grand Case, St. Martin · Leeward Islands (Anguilla to Antigua), Antigua & Barbuda · 18.103, -63.058
Updated : very low seaweed, beach grade A-, sea 85°F.
Veabird's call
Sunday is the call at A- with little seaweed, 85°F water and 20% rain.
May and June usually rate A-, a solid window to revisit this northwest coast.
Grades from Veabird's beach forecast; wording by AI (Muse Spark), checked against the forecast. Updated Nov 13, 01:00 UTC.
Tell me when Grand Case Beach is clear
One email when the seaweed clears or the beach grades A, at most once a week per beach. We only ask for your email address, and every email has a one-click unsubscribe.
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Questions about Grand Case Beach
Does Grand Case Beach get sargassum (seaweed)?
Yes, in season. Here the typical-year risk is moderate or higher in June and July and peaks in July (moderate). How much lands varies a lot by year, wind and currents.
What are the worst and best months for seaweed at Grand Case Beach?
Worst: July, though even then the typical risk is moderate. Best: August through May, when the risk is usually low.
How warm is the water at Grand Case Beach?
About 84°F in November. The sea is warmest in September and October (about 86°F) and coolest in February (about 80°F).
When is the best time to visit Grand Case Beach?
For warm water, low seaweed and dry weather, aim for January, February, March, May and December. May is usually the quietest of those, with about 10 rainy days and a sea near 83°F; seaweed risk is low.
Are there sargassum barriers or beach cleanups at Grand Case Beach?
Offshore barriers in Leeward Islands: few booms (some in St. Martin/St. Barths lagoons). Public cleanup: Collectivité crews on French side; hotels elsewhere; Orient Bay and Grand Cul-de-Sac frequently inundated. Typical clearing time: Same-day at resorts; windward bays can stay fouled for weeks in peak years.
When is hurricane season at Grand Case Beach, and how often do storms hit?
The Atlantic hurricane season runs June through November and peaks around September. A tropical storm passed within 86 miles of Grand Case Beach in 22 of the 55 seasons from 1971 to 2025, and a hurricane within 58 miles in 10. The riskiest stretch is around August 27, when the chance of a storm passing in any one week is about 6%; across all of August it is about 17%. Flexible bookings and travel insurance help in the peak weeks.
Sargassum season at Grand Case Beach Resorts
Sargassum risk at Grand Case Beach Resorts typically peaks around July (moderate: moderate or heavier seaweed on the beach in an estimated 30% of weeks). Lowest-risk months: January, February, March, April, May, August, September, October, November and December. Actual landings vary a lot by year, wind and currents; check the live conditions above.
Estimated share of weeks in each month with moderate or heavier seaweed on the beach. Veabird takes the landing season measured on Martinique's shores (Madininair's hydrogen-sulfide sensors beside stranding sites, 2018–2026) and scales it by how often NOAA AOML satellites see notable seaweed within about 20 km of this stretch of coast: 9% of weeks here on average, against 14% off Martinique, so 66% of that season. The satellite share (2016–2024, the top fifth of all coast-weeks, adjusted for this beach's exposure of 25%) measures seaweed offshore, not on the sand: off the Riviera Maya it reads high even in winter, when little lands. Very low under 10%, Low 10–24%, Moderate 25–44%, High 45–69%, Very high 70%+. Beach faces 320°; onshore winds from that direction push seaweed ashore. Satellite sargassum data: USF Optical Oceanography Lab (Sargassum Watch System) via NOAA AOML. The satellite record as open data.
The Leeward Islands month by month
Typical weather, water temperature, seaweed and crowds for every month: the best time to visit the Leeward Islands.
- The Leeward Islands in January
- The Leeward Islands in February
- The Leeward Islands in March
- The Leeward Islands in April
- The Leeward Islands in May
- The Leeward Islands in June
- The Leeward Islands in July
- The Leeward Islands in August
- The Leeward Islands in September
- The Leeward Islands in October
- The Leeward Islands in November
- The Leeward Islands in December
Weather, water & seaweed by month at Grand Case Beach Resorts
Average highs run from about 79°F in February and March to 85°F in September. The sea is warmest in September and October (about 86°F) and coolest in February (about 80°F). June is usually the driest, with about 9 rainy days; October is the wettest, with about 17 rainy days. Seaweed risk is usually lowest in December and highest in July.
| Month | Avg high | Sea | Rainy days | Sargassum |
|---|---|---|---|---|
| Jan | 80°F | 81°F | 11 | Very low |
| Feb | 79°F | 80°F | 10 | Very low |
| Mar | 79°F | 81°F | 10 | Low |
| Apr | 80°F | 81°F | 12 | Low |
| May | 82°F | 83°F | 10 | Low |
| Jun | 83°F | 83°F | 9 | Moderate |
| Jul | 84°F | 84°F | 13 | Moderate |
| Aug | 84°F | 85°F | 14 | Low |
| Sep | 85°F | 86°F | 16 | Low |
| Oct | 84°F | 86°F | 17 | Very low |
| Nov | 82°F | 84°F | 16 | Very low |
| Dec | 81°F | 82°F | 11 | Very low |
Monthly averages from 6 years of ERA5 reanalysis (Open-Meteo) for this area's 0.5° grid cell; rainy days have at least 1 mm (0.04 in). Sargassum is the typical-year estimate described above. Any given year can differ.
Cleanup & barriers
- Offshore barriers
- Few booms (some in St. Martin/St. Barths lagoons)
- Public cleanup
- Collectivité crews on French side; hotels elsewhere; Orient Bay and Grand Cul-de-Sac frequently inundated
- Resort crews
- Luxury resorts rake daily
- Typical clearing time
- Same-day at resorts; windward bays can stay fouled for weeks in peak years
Safety notes
US State Dept: Antigua & Barbuda, St. Kitts & Nevis, Anguilla Level 1; Sint Maarten Level 1; St. Martin (France) Level 2 per France (verify)
- Petty and vehicle crime in Philipsburg/Marigot; watch valuables
- Drive left on English islands, right on French side
- High hurricane exposure (Irma 2017, Luis 1995)
Check official advisories and local flags before swimming. Decomposing sargassum releases hydrogen sulfide; avoid heavy piles.
Things to do near Grand Case, St. Martin
- Nelson's Dockyard, Antigua
- Shoal Bay East, Anguilla
- Maho Beach plane-spotting, SXM
- Gustavia shopping, St. Barths
- Brimstone Hill Fortress, St. Kitts
- Barbuda Frigate Bird Sanctuary
Fly in for the best beach days
Suggested dates fall in December, typically the lowest-seaweed month ahead for Grand Case Beach Resorts. Change them to match the live forecast above.
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Nearest airports
- L'Espérance (Grand Case) (SFG), ~1 km
- Princess Juliana Intl (Sint Maarten) (SXM), ~9 km
Nearby resorts
- Love Beach Hotel Grand Case, St. Martin · 0 km
- Le Shambala Grand Case, St. Martin · 0 km
- Bleu Marine Resort Grand Case, St. Martin · 1 km
- Grand Case Beach Club Grand Case, St. Martin · 1 km
- Anse Marcel Beach Resort Grand Case, St. Martin · 2 km
- Secrets St Martin Hotels & Resorts Grand Case, St. Martin · 2 km
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