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 Phuket: Season, Monsoon and Crowds

An island on the Andaman clock

Phuket sits on the Andaman coast, and that matters more than any average temperature: its seasons run opposite to Koh Samui and the Gulf. When the Gulf islands are being rained on in November, Phuket is at its best.

Clear water and limestone off the Andaman coast

The dry season runs from November to April. Seas are flat, the sky is clear, the day-boats reach Phi Phi and Phang Nga without trouble, and the island is full. From May to October the south-west monsoon arrives: warm rain in bursts rather than all day, a green island, half-price rooms — and a sea with a genuine undertow.

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In short

Phuket seasons

November–April: dry season, calm sea, high prices
May–October: monsoon, warm rain, waves, half price
Best value: November and late April
Busiest and dearest: Christmas to mid-January
Opposite season to Koh Samui and the Gulf coast

The best weeks are the edges

November and early December, then late April, are the island's sweet spot: the sea has settled or not yet turned, prices sit below the Christmas peak, and the beaches have room on them. Locals will tell you the same.

Christmas to mid-January is the most expensive fortnight of the year and needs booking months ahead. February and March are hot, dry and reliable — the classic beach weeks — while April adds the heat of Songkran and the water fights that come with it.

Good to know

Planning around the weather

Red flags on the west coast are not decoration — people drown there every monsoon.
Phi Phi and Phang Nga day trips are calmest from December to March.
Songkran in mid-April is a national water fight; expect fun, and expect to get wet.
If your dates are fixed in the monsoon, consider the Gulf instead — its seasons are reversed.

Travelling in the monsoon

Monsoon does not mean a washout. Rain usually comes in heavy bursts and passes, and there is plenty of sun between them. What changes is the sea: the west coast builds real waves and rip currents, some beaches fly red flags for days, and the smaller day-boats stop running.

If you come between May and October, book on the sheltered side of the island for swimming, keep day trips flexible, and take the low prices as the compensation they are.

Month by month

January	Dry, calm, busy — peak season
February	Hot and reliable, flat sea
March	Hot, dry, excellent water clarity
April	Hottest month, Songkran mid-month
May	Monsoon begins, first swell, prices fall
June	Warm rain in bursts, green and quiet
July	Wet but with sun between showers
August	Wettest stretch, strong surf on the west
September	Rainiest month — many day-boats stop
October	Rain easing, sea still rough
November	Season turns — the value month
December	Dry and calm, prices climb to Christmas

Frequently asked questions

What is the rainy season in Phuket?

May to October, with September usually the wettest. Rain tends to come in heavy bursts rather than all day.

Can you swim in Phuket during the monsoon?

On calm days and sheltered beaches, yes — but the west coast gets real rip currents. If a red flag is flying, stay out of the water.

When is Phuket cheapest?

June to October. Room rates fall by half or more, and the island feels genuinely quiet.

Is Phuket better than Koh Samui in November?

Yes. November is the start of Phuket's dry season and the middle of the Gulf's rainy one, so the Andaman coast is the safer bet.

Travel guides

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Best time to visit Phuket