El Nino Watch
The highest forecast wave height near Samui over 72 hours, plus TMD Gulf wave warnings. High seas stop ferries and cut the island off.
Koh Samui watch
Main measure: the maximum significant wave height forecast for the next 72 hours (Open-Meteo Marine). A TMD high-wave warning for the Gulf raises it to at least 1. Andaman-only warnings are ignored: they do not concern Samui.
If the wave forecast is missing but a TMD rough-sea warning is in force, the factor shows 1 Watch.
Above 2 m, small boats stay in port and ferries may be cancelled: the island is then cut off (supplies, evacuation, water by barge). Only the airport remains, with limited capacity.
| Max wave height (72 h) | Factor level |
|---|---|
| below 1.5 m | 0 Normal |
| 1.5 to 2 m | 1 Watch |
| 2 to 3 m (small boats stay in port) | 2 Prepare |
| 3 m or more | 3 Act |
Cap: 3. Critical factor. Stale after 24 h without a marine forecast update.