Koh Lanta Weather by Month: Seasons and What to Expect

Dry season: November to April

• November: The transition into the dry season. Weather can still be mixed early in the month, with conditions generally improving and prices often below peak.
• December: Typically among the sunniest and calmest months, and the start of peak season, so expect the busiest and most expensive period around the holidays.
• January: Reliably dry-season conditions with calm seas, and still busy.
• February: Much like January: settled weather and strong demand for rooms and boat trips.
• March: Still dry and increasingly hot; sunshine is dependable and crowds ease slightly compared with mid-winter.
• April: Often the hottest and most humid part of the year, with the first pre-monsoon showers possible late in the month.

See the full best-time-to-visit guide

Rainy season: May to October

• May: The monsoon usually sets in. Expect a mix of sun and heavy showers, and note that Koh Rok and Koh Haa close from mid-May (dates set each year by the park).
• June: Wetter and greener, with rougher seas on some days; often good value.
• July: Showers and cloud alternate with bright spells; boat trips can be cancelled by swell.
• August: Similar to July, with the sea often at its choppiest.
• September: Commonly one of the wettest months on the Andaman coast, with long grey spells possible.
• October: Rain is often still heavy early in the month, easing towards its end; boats to Koh Rok and Koh Haa restart in November (dates set each year by the park).

Read what to expect in the rainy season

How to use this

If reliable sun and calm seas matter most, aim for December to March. If you want lower prices and quieter beaches and can tolerate showers, June and the shoulder weeks either side of the wet season can be good value. The transition months are the hardest to call, so if your dates are flexible, choose them close to travel using a live forecast.

Weather affects boat trips more than beach days: rough seas are what usually cancels an outing. Build a spare day into your plan for any must-do boat trip in the wet months. Thailand Voyager keeps a separate Koh Lanta weather page if you want a second reference.

Weather and Trip Planning

• Boat trips and island hopping: In the wetter months, seas are rougher, some boat trips run less often, and Koh Rok and Koh Ha close to visitors from mid-May to November, on dates set each year by the park. If your trip depends on island hopping or snorkelling, the drier season from roughly November to April is the safer choice.
• Quieter shoulder months: If you prefer quieter beaches and can stay flexible, the shoulder months are worth considering. Years vary, so treat monthly notes as tendencies. See the best time to visit Koh Lanta to weigh your options.
• Planning a rainy season trip: Find out what changes on the island from May to October, and how to plan around it, in Koh Lanta in the rainy season.