Koh Samui in the rainy season

📅 Updated September 2026 · ⏱️ 8 min read · ✍️ The Koh Samui Tours team

Every autumn the same message arrives on our WhatsApp, in every language: we have booked for November, is it going to rain the whole time? The honest answer is no, but November is a real monsoon month, and a trip planned around four boat days will be disappointed. A trip planned around the island itself will not. This is how the wet season on Koh Samui actually behaves, what it cancels, and what we do with a grey day.

When it rains, and how much

Samui runs on the Gulf of Thailand calendar, not Phuket's. While the Andaman coast gets its monsoon from May to October, Samui stays mostly dry, and its own rainy season arrives later and shorter, carried by the north-east wind from October to mid-December. Here is what the long-term averages look like on the north-east coast:

Two things those numbers hide. Rain here rarely falls as a gentle all-day drizzle: it comes as loud, warm downpours of twenty minutes to a few hours, and the temperature barely moves, still around 27 to 30 °C. And the sea matters more than the sky: a dry but windy day in November can cancel a boat that a rainy but calm day in October would not. Our month-by-month guide has the full year, if you are still choosing your dates.

What the rain cancels, and what it does not

Ang Thong usually closes in November. The marine park shuts its waters to visitors when the sea is at its worst, and the long open-water run there is exactly what the north-east wind makes unpleasant. If Ang Thong is the reason for your trip, do not come in November; our Ang Thong guide explains when it reopens.

Koh Tao is a maybe. The ferries and speedboats keep sailing on most days, but the crossing gets rough, visibility on the reefs drops, and a few days a month are cancelled outright. People who get seasick should not pick this month to find out.

The short hops often still work. Koh Madsum and Koh Tan sit a few kilometres off the south coast, and the run out stays close to shore. They are the boat trips most likely to go ahead in a wet month, which is worth knowing when you pick your day trip.

Our rule is the same all year: every sea trip is confirmed the evening before, weather permitting, and if we cancel for the weather you choose between another date and a full refund. The practical advice is to book any boat day early in your stay, so that a cancelled Tuesday can become a Thursday instead of nothing.

Seven things that work in the rain

1. A Thai cooking class

The rainy day activity we recommend first, because the rain is irrelevant to it. Four hours with a Samui family, a walk through the market to learn what the herbs actually are, and four dishes you cook and eat yourself. It runs under a roof whatever the sky does: Thai cooking class with a Samui family.

2. The temples, inside and out

Temple halls are made for this weather: cool, quiet, and full of murals nobody looks at on a sunny day. The southern temples are the best wet-day route on the island, five stops in twenty kilometres with no entrance fee, and the mummified monk of Wat Khunaram sits in his glass case whatever the forecast. Our guide to the southern temples has the route; if you would rather be driven, the southern temples loop does it in a morning.

3. The waterfalls, the morning after

This is the one thing the wet season does better than the dry one. From October to January the rivers run and Na Muang 1 pours eighteen metres over its purple rock into a pool worth swimming in; by April it can be a trickle. The rule is to go the morning after heavy rain, not during it: the paths are slippery and the water rises fast. Our waterfalls guide ranks them, and waterfalls and zipline is a half-day we schedule for exactly these months.

4. Muay Thai at Phetch Buncha

An evening under a roof with a live band, a full card of fights and a crowd that follows every point. Phetch Buncha has cards on Monday, Wednesday and Saturday, and tickets start at ฿1,500 through our Muay Thai stadium page. Rain outside only makes it louder.

5. An elephant sanctuary

The elephants do not mind the rain and neither, after ten minutes, will you: bring a light rain jacket rather than an umbrella. The sanctuary we work with has no riding and no shows, and visitors watch from a raised walkway. Before choosing any camp, read our guide to ethical elephant sanctuaries.

6. The markets

Morning markets are covered and busiest when nobody can go to the beach: fish, curries by the bag, fruit you have never seen. Evening walking streets are more exposed, a downpour at seven can empty Fisherman's Village in minutes and refill it by eight. Keep a flexible evening, and check the night market calendar for the day.

7. A massage, a long lunch, a slow afternoon

The least exciting advice and the most followed. Massage huts all over the island take walk-ins in cash, and a two-hour Thai lunch in a shophouse restaurant while the rain hammers the tin roof is a very Samui way to spend an afternoon.

What we would not do in the rain

• Ride a rented scooter up a hill road. The steep concrete climbs to the viewpoints turn slick in minutes, and wet-season scooter falls fill the island's clinics every week. Our guide to the viewpoints and the roads up says which ones need a 4×4.
• Drive the interior tracks after a storm. The roads to Khun Si waterfall and the Secret Buddha Garden are rough in the dry season and worse in the wet one. Go with a driver or wait for a dry day.
• Swim under a red flag. The north-east wind builds a shore break on Chaweng and Lamai from November into January. Lipa Noi and the west coast stay flatter, as we explain in Nathon and the west coast.
• Plan a snorkelling holiday. Visibility drops everywhere. Keep the reef for another trip, or for a calm morning if one comes.

What to pack for a wet-season trip

The rain here is warm, so the aim is not to stay dry but to stay comfortable while you get wet and dry off again. A few things make a real difference between October and mid-December.

• A light rain jacket with a hood. Not a heavy waterproof, you will boil in it at 28 °C, and not an umbrella, which the north-east wind turns inside out in seconds.
• Sandals with grip. Flip-flops are dangerous on wet temple steps, tiled hotel floors and waterfall paths. A pair of sports sandals you can walk through puddles in is the single most useful item in a monsoon bag.
• Quick-dry clothes, and more of them. Cotton stays damp for days in this humidity. Pack fewer jeans and more light synthetic layers, and plan on using the hotel laundry once.
• A dry bag and a waterproof phone pouch. For scooter-free taxi rides between downpours, market mornings and any boat that does sail.
• Mosquito repellent. Standing water after the rain means more mosquitoes at dawn and dusk. Dengue is present on the island all year, so use repellent at those hours, and see a doctor if a fever follows a few days of bites.
• Motion-sickness tablets. If you are attempting Koh Tao or a longer crossing, take them before you board, not once the swell has started.
• Something to do indoors. A book, a downloaded film, a pack of cards. The grey spells of two or three days are when people who planned for them enjoy themselves most.

Everything else can be bought on the island, including cheap ponchos at any 7-Eleven, but reef-safe sunscreen is worth bringing from home: the sun between showers is as strong as ever. Our packing list and health notes cover the rest.

Where to stay when the monsoon blows

In the dry season, your hotel choice is about beaches and budget. In the wet season, two more questions matter: what the sea in front of you does when the north-east wind blows, and how far you are from things to do under a roof.

The east coast takes the wind. Chaweng and Lamai face the monsoon directly, and from November the shore break and red flags can keep you out of the water for days. They make up for it with restaurants, massage places and covered markets within walking distance, which counts for a lot when it pours.

The west coast stays calmer, and quieter. Lipa Noi and the coast around Nathon are flatter for swimming, as we said above, and the sunsets are better when the sky clears. The trade-off is distance: you are further from the north-east, where most restaurants, evening markets and our pick-ups are concentrated, so plan on a taxi or a Grab for most outings.

The north coast is the compromise. Bophut, Maenam and Bangrak keep you close to the airport, the piers and Fisherman's Village, so a cancelled boat becomes a lazy afternoon rather than a long ride.

Whichever beach you choose, a few details in the listing matter more than usual: a covered terrace or balcony where you can sit out a downpour, a pool that makes up for a rough sea, and a hotel at the end of a paved road rather than a dirt track that turns to mud. In low season, a flexible rate costs little and lets you move if a stretch of coast disappoints.

Our guide to where to stay on Koh Samui compares every area, and the beaches guide compares them coast by coast.

Is the rainy season worth booking?

October and the second half of December, yes, without hesitation: lower prices in October, fewer people, green hills and full waterfalls, and most days still have long dry stretches. November is a different trip. If the sea is the point, go elsewhere or come in February. If you want the island, its food, its temples and a few quiet beaches, and you are happy to read a book while it pours, November is the cheapest and emptiest Samui you will ever see. Our budget guide shows what the low season saves.

Frequently asked questions