Rain, sunshine, wind and sea conditions vary within every season. Check an up-to-date official forecast and marine warnings close to travel.
Seasonal comparison
| Period | Phuket — Andaman coast | Koh Samui — Gulf coast |
|---|---|---|
| December–January | Generally drier; popular beach period | December can still be wet; conditions often improve into January |
| February–March | Generally dry with settled beach conditions | Often among the drier months |
| April | Hot, with changing conditions possible | Generally relatively dry and hot |
| May–August | Southwest monsoon can bring rain and rougher seas | Summer months may suit beach holidays, though showers still occur |
| September–October | Typically wetter, especially September and October | Rain generally increases into the later part of this period |
| November | Transition towards drier conditions | Typically one of the wettest months |
Phuket weather pattern
December to March is generally Phuket's drier period. September and October are typically wetter. During the southwest monsoon, the Andaman coast can have rough seas, strong currents and disrupted boat trips even when rain is intermittent.
Travellers visiting outside the driest months can still have sunny periods, but should allow flexibility for marine activities and follow red-flag beach warnings.
Koh Samui weather pattern
February to April is generally relatively dry. Summer months may also suit beach holidays because Samui's seasonal pattern differs from the Andaman coast. October to December is typically wetter, with November often especially wet in long-term climate data.
Conditions vary around the island and from year to year. Short tropical showers do not necessarily mean a full day of rain, while a severe system can affect transport and sea conditions.
What season changes about accommodation
- Beach use: swimming safety and water clarity may change with wind, swell and rainfall.
- Hillside access: heavy rain can make steep roads and outdoor steps less comfortable.
- Boat plans: excursions can be changed or cancelled for safety.
- Availability: popular travel periods may have less choice; do not assume that a lower-season rate guarantees suitable weather.