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.

Andaman Sea · Seasons & weather

Best time to visit Ranong

November to April is dry and easy. May to October is the wettest weather in Thailand, and the hot springs are the one thing that does not care.

The wettest province in the country

Ranong records more rain than anywhere else in Thailand — comfortably over four metres a year in the wettest spots, against roughly one metre in Bangkok. The mountains behind the town catch the south-west monsoon and wring it out, which is why the hills here are rainforest rather than scrub.

That gives the year a very clear shape. November to April is the dry season, and it is genuinely dry. May to October is the wet one, and it is genuinely wet: not an afternoon shower, but days of rain, low cloud on the ridges and a sea that stays grey.

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In short

Ranong seasons

November–April: dry season, calm sea, boats on full schedule
May–October: the wettest weather in Thailand, islands mostly closed
Best months: December to February
Hottest: April
Hot springs at Raksawarin: around 65°C, open all year

November to April, the season

November is the reopening: the rain stops, the rivers are still full and everything is green. December to February is the best weather of the year, warm and dry with clear evenings, and it is when the boats to Koh Phayam and Koh Chang Noi run on a full schedule.

March and April are hot and hazy, with April the hottest month. The sea is at its calmest through this whole stretch, which is what matters if the islands offshore are the reason you came to Ranong at all.

Good to know

Planning around the weather

Check the Koh Phayam boat schedule before booking anything from May to October.
Many island bungalows shut for the monsoon — confirm your booking is actually open.
The Andaman calendar here is the opposite of Koh Samui's: dry when Samui is wet.
Ranong is a border town, so hotels fill mid-week with visa traffic as well as tourists.

May to October, and the hot springs

Through the monsoon the rain is heavy and persistent, boat schedules to the islands are cut back or suspended in bad weather, and many island bungalows close entirely for the season. Ranong town itself keeps working: it is a border town and a fishing port before it is a resort.

This is where the hot springs earn their place. Raksawarin park, on the edge of town, runs at around 65 degrees all year and is at its best when the air is cool and wet. A rainy week in Ranong is a poor beach holiday and a perfectly good spa one.

Month by month

January	Dry and warm — peak season, full boat schedule
February	Dry, calm and clear, the best month for the islands
March	Hot and dry, hazier air
April	Hottest month, Songkran mid-month, season ending
May	The monsoon arrives, boats start to thin out
June	Heavy rain, many island bungalows now closed
July	Very wet, low cloud, limited crossings
August	One of the wettest months in Thailand
September	Wettest and quietest — islands largely shut
October	Rain easing late in the month, islands reopening
November	Green, dry and calm — the best value month
December	Dry and warm, prices climbing towards New Year

Frequently asked questions

When is the best time to visit Ranong?

November to April, and December to February in particular. That is the dry season, with calm sea and boats to the islands running on a full schedule.

Why does Ranong get so much rain?

The mountains behind the town catch the south-west monsoon head-on. It is the wettest province in Thailand, with over four metres of rain a year in places.

Can you go to Koh Phayam in the rainy season?

Sometimes. Crossings are reduced or cancelled in bad weather from May to October, and many bungalows close for the season, so check before you commit.

Are the hot springs worth it in the rain?

Yes — arguably more so. The Raksawarin pools run at around 65 degrees year round and are best when the air is cool and damp.

Travel guides

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