Trang lies in the tropics, so it is warm all year — typically in the low 30s °C by day, with warm sea temperatures. What changes is the wind and rain. The dry season, roughly November to April, brings calm seas and clear water; the south-west monsoon, roughly May to October, brings rain, wind and waves to the Andaman coast.
Koh Kradan month by month
| Month | Weather | Crowds | Verdict |
|---|---|---|---|
| January | Dry, sunny, calm sea | High | Excellent — peak conditions |
| February | Dry, sunny, calm | High | Excellent; Underwater Wedding season |
| March | Hot, dry | Moderate | Excellent; clear water |
| April | Hot, occasional storms | Moderate (Songkran busy) | Very good; season winding down |
| May | Monsoon arrives, showers | Low | Mixed; some resorts close |
| June | Rain and swell | Very low | Rough crossings likely |
| July | Rain and wind | Very low | Many resorts closed |
| August | Rain and wind | Very low | Many resorts closed |
| September | Often the wettest month | Very low | Least recommended |
| October | Rain easing late | Low | Mixed; resorts start reopening |
| November | Drier, some showers | Rising | Good; season starts |
| December | Dry, sunny | Very high (holidays) | Excellent; book ahead |
November to April — the dry season
The north-east monsoon brings dry, sunny weather to the Andaman coast. The sea calms, the water clears and all boats and resorts run. December to February is the busiest period — especially around Christmas, New Year and Chinese New Year — so book rooms and boats early. March and April are hot, quieter and often have the clearest water.
May to October — the green season
The south-west monsoon brings rain, wind and waves straight onto Kradan’s side of the coast. It does not rain all day, every day, but crossings can be rough or cancelled, the reef is often murky, Emerald Cave may be closed when the sea is high, and many Kradan resorts close or run reduced services. If you come in the low season, check that your resort is open and allow flexible days.
Holidays and festivals
- Underwater Wedding (around Valentine’s Day): Trang’s famous seabed wedding ceremony; dates and venues vary — check before you plan around it.
- Songkran (Thai New Year, 13–15 April) brings crowds of Thai visitors.
- Christmas, New Year and Chinese New Year are the busiest weeks of the year.
Snorkelling by season
- December to April: calmest sea and best visibility; all the 4-islands stops are usually accessible.
- November and early May: shoulder months with good conditions on many days.
- June to October: often poor visibility and rough sea; trips may be cancelled.
