Satun lies less than seven degrees north of the equator, so it is warm all year — typically 30–33 °C by day, with sea temperatures around 28–30 °C. What changes is the monsoon. The short answer: November to April is the dry season, with calm seas, the best visibility and every island open. From around mid-May to mid-October the south-west monsoon brings rain and swell, and most park islands close to visitors — though Koh Lipe itself stays open.
Tarutao month by month
| Month | Weather | Crowds | Verdict |
|---|---|---|---|
| January | Dry, sunny, calm sea | High | Excellent — peak conditions |
| February | Dry, sunny, calm | High | Excellent; clear water |
| March | Hot, dry | Moderate | Excellent; quieter after mid-month |
| April | Hot, occasional storms | Moderate (Songkran busy) | Very good; warmest sea |
| May | Monsoon arrives, showers | Low | Mixed; park islands close mid-month |
| June | Rain and swell | Low | Lipe only; rough crossings possible |
| July | Rain and wind | Low | Lipe only; low-season trips |
| August | Rain and wind | Low | Lipe only; lowest prices |
| September | Often the wettest month | Very low | Least recommended |
| October | Rain easing late | Low | Mixed; islands reopen mid-month |
| 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 down and visibility on the reefs is at its best. All the park islands are open, park bungalows on Koh Tarutao and tents on Koh Adang are available, and the island-hopping speedboats from Koh Lanta and Phi Phi run. December to February is the busiest and most expensive period, especially around Christmas, New Year and Chinese New Year; March and April are hotter and a little quieter.
Mid-May to mid-October — the green season
The south-west monsoon brings rain, wind and waves. It does not rain all day every day, but crossings from Pak Bara can be rough and are sometimes cancelled. The national park normally closes Koh Tarutao, Koh Adang and most other islands to visitors from around 16 May to 15 October — the exact dates are announced each year — to protect visitors and give the reefs a rest. Koh Lipe stays open, many resorts drop their prices sharply, and a few sheltered low-season snorkelling trips keep running.
Holidays and festivals
- Songkran (Thai New Year, 13–15 April) brings crowds of Thai visitors and water fights.
- Loy Rua, the Urak Lawoi boat-floating ceremony, takes place twice a year around the full moons of the sixth and eleventh lunar months — usually in May–June and October–November.
- Malaysian school holidays and long weekends fill the Langkawi ferries.
Diving and snorkelling by season
- December to April: best visibility and calmest sea; the full range of sites is accessible.
- November and early May: shoulder months with good conditions most days.
- June to October: limited, sheltered sites only, depending on weather.