Seasonal· St Martin (French side)· Leeward Islands
Winter Northerly Swell (Marigot & Grand Case)
18° 6.0′ N · 63° 6.0′ W · approximate
Long-period north to north-west ground swell from North Atlantic winter storms funnels down the Anguilla Channel onto St Martin's north-west coast. It can turn Marigot, Friar's Bay, Happy Bay and Grand Case from calm anchorages into breaking, rolling lee shores within hours.
Practical
Coordinate approx: in the Anguilla Channel off Marigot, the swell's entry path. Météo-France issued an orange 'waves-submersion' alert on January 10, 2025 for a north to north-west swell of 1.2-1.8 m at a 12-13 second period entering through the Anguilla Channel. That alert named the Terres-Basses to Grand Case coast as most exposed and warned that boat moorings were likely to break loose. On December 9, 2022, an orange alert for a north-north-east swell of about 3.5 m at a 13-16 second period warned of heavy strain on moorings, with advice to avoid going to sea. The Marigot and Grand Case anchorages are good in E-ESE trades but go swelly with any northerly component, and the dinghy landing at Grand Case becomes hazardous. When a swell is forecast, move early into Simpson Bay Lagoon (bridge openings stop in heavy weather; check the schedule) or round to the south coast. Check Météo-France Antilles marine bulletins, and watch the swell period as well as the wind.
Best for
Deciding when to leave the north-west anchorages
Season
Mainly December-April, with cold fronts and North Atlantic storms