Koh Samui in November: How Bad Is the Rain, Really?

November is Koh Samui's wettest month: about 490 mm of rain on twenty days, which means rain on two days in three, and rough seas on the east coast. That is the short answer to the question people ask most about Samui, "I booked November, how bad is the rain?" The long answer, with the numbers attached, is below, so you can decide for your own dates.

The numbers, month by month

These are the long-term averages published by the World Meteorological Organization from Thai Meteorological Department data for the Ko Samui station.

November is the wettest month by a distance. Almost 500 mm, a quarter of the whole year's rain, in one month. October is second. December is still wet but half of November.

It rains on two days in three, not every day. Twenty rain days in November, which also means about ten dry ones. And the average rain day carries about 25 mm, which is a heavy shower or a wet hour, not a washout. Washouts happen, and the averages hide them.

February to April is the reliable stretch, at 5 to 8 rain days a month. January still has 11. From May to September the island gets a dozen or so shower days a month and stays warm.

What November is like

The sea causes more trouble in November than the rain does.

From mid-October to early December the northeast monsoon pushes onto Samui's east coast, which is where Chaweng and Lamai are. Red flags go up on the beaches and swimming is banned on the rough days. Ferry cancellations are rare from January to April and common from October to early December, with October the worst month for storms in the Gulf. A tropical depression can stop the boats for anything from two days to a week. If your plan involves Koh Phangan or Koh Tao, plan around the boats.

The west coast, sheltered by the ridge through the middle of the island, is calmer in October and November. It is also where the sunsets are.

The ring road is fine wet. The inland mountain roads are steep and slippery when it rains. If you would not ride at home in heavy rain, do not ride here in it.

How bad does it get

Tropical Storm Pabuk, January 2019, was the first tropical storm to hit southern Thailand in nearly thirty years. Bangkok Airways cancelled all flights to and from Samui, ferries stopped, and tens of thousands of visitors left Koh Phangan and Koh Tao ahead of it. A man drowned at Samui after his family swam past the red flags.

The southern Thailand floods of late November and December 2025 hit the mainland provinces hard. On 8 December the Tourism Authority of Thailand's update listed Surat Thani, including Samui, Phangan and Tao, as "fully accessible, with attractions, transport services, and airports operating normally," with the note that "marine transport may adjust schedules due to weather conditions."

The realistic November risk is a lost day or two, most often a boat, occasionally a flight. Build that into the plan.

Is it worth the risk?

If your dates are flexible, wait for the second half of December, or come between February and April.

If your dates are fixed, go, and plan for the sea. Put the ferry crossings early in the trip, not the day before a flight. Book a room with a pool and a view rather than counting on the beach. Keep one day's worth of indoor plans in your pocket.

What to do when it rains

Central Samui. The open-air mall in Chaweng, open 10:00 to 22:00, with a Major Cineplex inside showing current releases.

Cook. Cooking schools around Bophut and Fisherman's Village run half-day classes with a market visit and hotel pickup, morning or evening, for roughly 2,000 to 3,000 baht.

Muay Thai. Fight nights run three evenings a week from 21:00 at the stadium on the Chaweng to Choeng Mon road, tickets from 1,500 baht. Under a roof, and loud.

Temples between showers. Big Buddha and Wat Plai Laem are fifteen minutes from Chaweng and take about an hour together. Shoulders and knees covered, shoes off inside.

Quick answers

How bad is the rain in Koh Samui in November? It is the wettest month, about 490 mm on twenty rain days. That is rain on two days in three, mostly as heavy showers, with the occasional washout and rough seas on the east coast.

Is Koh Samui worth visiting in November? Yes if your dates are fixed and you plan around the sea rather than the rain: ferries early in the trip, a buffer before flights, indoor options ready. If you can move, late December to April is better.

Which month has the best weather in Koh Samui? February to April: 5 to 8 rain days a month and the calmest sea.

Do the ferries run in November? Most days, yes. Cancellations are common from October to early December when the Gulf is rough, and a tropical depression can stop boats for two days to a week. Do not put a crossing on the day before a flight.

Rainfall and temperature figures are World Meteorological Organization long-term averages for the Ko Samui station, read in September 2026. Prices and hours change without notice.