Koh Samui in October: Weather, Season and What to Do

October is when Koh Samui's rainy season starts to build: noticeably more cloud and showers than the dry months, but not yet constant rain. If you stay flexible, chase the sun between downpours and use the last calm boat days of the year, October can still be a lovely, affordable time to visit.

At a glance

Weather in October

With around 16 rain days and roughly 290mm of rainfall, October is noticeably wetter than the preceding months, though still well below November's peak. Most showers are heavy but come in bursts, often in the late afternoon or evening, with sunshine returning in between. By mid to late October, wind on the Gulf side picks up and the sea gets choppier, especially off the east and north coasts. For more on the mechanism behind this, see our article Koh Samui weather and the truth about the rainy season.

Worth packing: a light rain jacket or small umbrella and a waterproof phone pouch — with showers this short and heavy, you're usually dry again within the hour.

What you can do in October – and what you can't

Ang Thong National Park is still open as normal throughout October – the official closure only starts on 1 November. If you want to see the famous emerald lagoon and the viewpoint, this is your last easy month, ideally with a morning departure while the sea is calmest:

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For snorkelling, the south side of the island often still works well in October, around Koh Madsum (Pig Island) and Koh Tan, where the water tends to be calmer than on the east and north coasts:

from 1,450 THBPig Island Snorkeling Koh Madsum & Koh Tan Speed Boat Economy Tour★★★★★4.79 from 283 reviews

For beach days, the north coast (Maenam, Bophut) is usually less exposed to the wind than Chaweng or Lamai. If a boat trip gets cancelled at short notice, an air-conditioned island tour with a temple stop, a shopping mall, or a night market are good backup plans – more ideas in our Top 10 rainy day activities. A Thai massage or a quiet spa afternoon also bridges a wet morning nicely, before the sun often returns in the afternoon.

Festivals and events in October

The Vegetarian Festival (Thetsakan Kin Che) runs from 10 to 18 October in 2026 – a nine-day Taoist festival you can experience on Koh Samui at the Chinese temple in Maenam and the Guan Yu shrine in Hua Thanon, with vegetarian food stalls and ceremonies. Shortly after, on 11 October, is Ngan Duan Sib (Sart Thai), a day of remembrance for deceased relatives with a small parade in Nathon. More on both in our Top 10 events in Thailand.

On 26 October comes Wan Ok Phansa, the end of Buddhist Lent — one of Thailand's nationwide public holidays with a 24-hour alcohol sales ban at supermarkets, convenience stores and most shops. Hotel bars and restaurants are generally exempt, but it's worth buying drinks a day early just in case.

Fruit in season

October marks the start of the smaller winter pineapple harvest, which runs through December alongside the main summer crop earlier in the year. Most other market staples — papaya, dragon fruit, guava and coconut — are available year-round anyway. More seasonal timings in our Top 10 fruits in Thailand.

Frequently asked questions

Does it rain a lot on Koh Samui in October?

Noticeably more than in the dry months, with around 16 rain days and about 290mm of rainfall. Most showers are short and heavy rather than constant, with sunshine in between. November, not October, is the wettest month of the year.

Is October a good time to visit Koh Samui?

Yes, if you like low prices, small crowds and still fairly stable weather — as long as your plans allow for rain days and flexible boat bookings. If you need guaranteed dry weather, aim for January to March instead.

Is Ang Thong National Park still open in October?

Yes, it's open as normal throughout October. The official closure for rough seas only starts on 1 November and runs through 15 December 2026.

What's happening on Koh Samui in October?

Mainly the Vegetarian Festival (10–18 Oct) and Ngan Duan Sib (11 Oct), plus the Buddhist holiday Wan Ok Phansa on 26 Oct with its alcohol sales ban. Recurring sporting or nightlife events like the regatta or Full Moon Party continue regardless of season — details in our Top 10 events in Thailand.

The rainy season continues into November; before that, see how the transition builds in September. For the full-year overview, read The best time to visit Koh Samui, and for everything about the national park itself, see our Ang Thong article.