When is the best time for diving on Koh Tao?

Roughly March to September, when seas are calm and visibility at its best. Diving runs year-round, but October to December brings wind, rain and reduced visibility.

When is the rainy season on Koh Tao?

October to December, peaking in November. Like the rest of the Gulf, Koh Tao stays largely dry through the European summer months.

Can ferries to Koh Tao be cancelled?

Yes — in the November–December monsoon, rough seas occasionally halt crossings from Chumphon and Surat Thani for a day or two. Build slack into travel plans in those months.

When can you see whale sharks at Koh Tao?

Sightings happen year-round and are never guaranteed. Many divers report clusters of sightings in the settled months around March–May and again around September–October.

Best Time to Visit Koh Lanta: Season and Closures

A seasonal island, more than most

Koh Lanta sits on the Andaman coast, so its year runs the same way as Phuket's and the opposite way to Koh Samui's: dry from November to April, wet from May to October. What makes Lanta different is how strongly the island itself follows that calendar.

Clear Andaman water on a calm high-season day

In high season the whole west coast is open, the sea is flat, and boats run to Phi Phi, Krabi and the Four Islands every morning. In low season the southern half thins out dramatically — restaurants, dive shops and whole resorts close for months, and the ferry timetable shrinks to a fraction. The island does not stop, but it does empty.

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In short

Koh Lanta seasons

November–April: dry season, calm sea, everything open
May–October: monsoon, half price, much of the south closed
Best value: November and late April
Busiest and dearest: Christmas to mid-January
Same season as Phuket, opposite to Koh Samui

The best weeks: November and late April

November is the turn: the rain has usually finished, the island is at its greenest, everything has just reopened and prices have not climbed yet. Late April is the mirror image — still dry, still calm, and noticeably cheaper than February.

December to February is peak season: the most reliable weather of the year, and the highest prices, with Christmas and New Year needing to be booked months ahead. March and April are hot and dry, and April is the hottest month of the year as well as Songkran, the national water festival in mid-April.

Good to know

Planning around the weather

If you travel May to October, confirm your hotel and its restaurant are actually open.
Day boats to Phi Phi and the Four Islands are most reliable from December to March.
Songkran in mid-April is a country-wide water fight; expect to get soaked.
The bridges mean road transport runs all year, even when the ferries stop.

Low season: what you gain and what closes

From May to October the price of a room can fall by half or more, the island is green and the beaches are close to empty. Rain usually comes in heavy bursts rather than all day, and there is plenty of sun in between — especially in May, June and early October.

The trade-off is choice. Boats to Phi Phi and the islands run less often or not at all in the roughest weeks, the south of the island loses much of its eating out, and the sea gets rough enough that swimming is not always sensible. Because the bridges connect Lanta to the mainland, minivans keep running all year — so getting there is never the problem.

Coconut palms behind the beach in the green season

Month by month

January	Dry, calm, busy — the peak of the season
February	Hot and reliable, flat sea, high prices
March	Hot and dry, excellent water clarity
April	Hottest month, Songkran mid-month, season ending
May	Monsoon starts, prices drop, places begin to close
June	Warm rain in bursts, green and very quiet
July	Wet, with sun between the showers
August	One of the wettest months, rough sea
September	Wettest and quietest — much of the south is shut
October	Rain easing, the island reopens late in the month
November	Everything open again — the best value month
December	Dry and calm, prices climb towards Christmas

Frequently asked questions

When is the rainy season on Koh Lanta?

May to October, with August and September the wettest. Rain tends to arrive in heavy bursts rather than lasting all day.

Does Koh Lanta close in low season?

Partly. The north around Saladan and Klong Dao stays open all year, but many places from Klong Nin southwards shut from about May to October.

When is Koh Lanta cheapest?

June to October, when room rates often fall by half. Just check that your hotel and the restaurants near it are open.

Is Koh Lanta better than Koh Samui in January?

For weather, yes — January is the middle of Lanta's dry season, while Samui sits on the opposite calendar and has just come out of its rainiest months.

Travel guides

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Best time to visit Koh Lanta