Koh Samui sits in the Gulf of Thailand, and its rainy season runs on a different calendar from Phuket’s: the heaviest rain comes from October to December, with the peak in November. Below are Thai Meteorological Department (TMD) normals for the island’s station, TMD’s outlook for November 2026, what is closed, what still works on a wet day and when to choose Phuket instead. Checked on 27 October 2026.
Koh Samui weather in November: TMD numbers
These are 1991-2020 normals for the Ko Samui station (48 550). TMD counts a rainy day from 0.1 mm. Koh Phangan and Koh Tao have no TMD stations of their own, so Samui is the nearest reference.
| November | Ko Samui (48 550) |
|---|---|
| Average high | 29.7 °C |
| Average low | 24.1 °C |
| Rainfall | 444.6 mm |
| Rainy days (0.1 mm or more) | 18.7 |
| Days with thunderstorms | 8.2 |
| Wettest single day, 1991-2020 | 363.9 mm |
| Humidity | 86%, the highest of the year |
| Prevailing wind | east |
How November compares with the months around it:
| Month | Samui rain, mm | Samui rainy days | Phuket rain, mm |
|---|---|---|---|
| October | 294.9 | 19.3 | 336.0 |
| November | 444.6 | 18.7 | 178.2 |
| December | 263.1 | 14.2 | 82.0 |
| January | 126.8 | 11.1 | 49.9 |
| February | 64.3 | 5.6 | 24.0 |
November alone brings 22% of Samui’s annual rain (our calculation from the TMD table). All twelve months are on Koh Samui weather by month.
TMD outlook for November 2026
TMD issued its cool season outlook on 9 October 2026 and had not updated it by 27 October. For the east coast of the south, where Samui is, it says:
- November: minimum temperatures of 24-26 °C, thunderstorms over 60-80% of the area, heavy to very heavy rain in places, mostly from Chumphon southwards
- Mid-October to early January: heavy rain in many places, with possible flash floods, run-off from the hills and rivers bursting their banks
- Waves in the Gulf of Thailand of 2-4 m at times
- In November and December low-pressure systems may become tropical storms crossing the Gulf and the south, with storm surge and waves of 3-4 m, up to 4-5 m in places
For the coming week, use the TMD 7-day forecast: Samui falls under Southern (East Coast), with wind and wave height.
Sea, beaches and boats
The prevailing November wind at the Samui station blows from the east. That puts the swell on the east coast, where Chaweng and Lamai face open water. The west coast around Lipa Noi is on the lee side. This is our reading of the TMD wind data, not a wave measurement for each beach, so the flag and lifeguards on the day still decide.
Boat days are the hardest part of a November trip. Tours to Koh Tao, Nang Yuan and Phangan run in calm weather and can be cancelled when the sea is up, so keep them flexible and pay for them close to the date. Ferry times and operators are on Samui to Koh Phangan and Koh Tao.
What’s closed and open
| Place | Status in November 2026 | Foreign adult fee | Source |
|---|---|---|---|
| Ang Thong Marine Park | closed 1 November-15 December, opens 16 December | THB 300 on Ko Wua Talap and Ko Mae Ko | DNP |
| Koh Tao and Nang Yuan | open, no national park, trips depend on the sea | no DNP fee | our trip page |
| Big Buddha, Wat Phra Yai | open, on land | no fee found | our sight page |
| Na Muang waterfalls | open, full of water, slippery trails | no official fee found | our sight page |
Ang Thong’s closure is in the DNP closure table (data as of 7 January 2026), the fee in the DNP table for individuals (2 June 2023). The park is the most popular day trip from Samui, so a November visit misses it entirely.
What to do on Koh Samui in November
Plan the trip around things that work on land and keep the sea for whatever calm mornings you get:
- Temples and viewpoints. The Big Buddha is 2.8 km from the airport and fine between showers
- Waterfalls. Na Muang has the most water after the rains, but the upper trail is steep and slippery: go to the first fall only, and not during a downpour
- Fisherman’s Village in Bophut. The old fishing street by the pier, see Bophut
- Spa, cooking classes, cafes. Book on the day, when you see the forecast
- Boat trips. Only on a calm day with a flexible booking. Ang Thong is closed until 15 December
More ideas are on Samui excursions and in the Koh Samui holiday guide.
Events in November 2026
Loy Krathong falls on the full moon of the 12th Thai lunar month. TAT gives the end of Buddhist Lent, the 11th month full moon, as 26 October 2026, which by our count puts Loy Krathong on Tuesday 24 November 2026. As of 27 October neither TAT nor Samui’s municipality had published a 2026 programme for the island. We found no other confirmed November events on Samui.
Crowds and hotel occupancy
The Ministry of Tourism and Sports (MOTS) reports occupancy for Surat Thani province as a whole, which includes Samui, Phangan, Tao and the mainland. It was 73.70% in November 2025, against 70.84% in October and 83.54% in December, the highest month of the year. November is one of the quietest months, which is the upside of the weather. We do not publish hotel rates until we collect our own dated measurements.
When Phuket is the better choice
If you can choose the island, Phuket is drier in November: 178.2 mm against Samui’s 444.6 mm by TMD normals, with the wind blowing offshore on its west coast beaches. The side-by-side table for all twelve months, thunderstorm days and record downpours is on Phuket or Koh Samui in November, and Phuket’s month in detail on Phuket in November. Pattaya and Hua Hin are drier still, see Thailand in November. You can also combine the two islands: Phuket to Koh Samui is a 55-minute flight.
Should you go to Koh Samui in November?
Go if:
- you are coming for a villa, a spa or work and do not need the beach every day
- you have flexible bookings and spare days
- you want the island at its quietest
Choose another month or island if:
- the sea and island trips are the point of the holiday: February to April is Samui’s best time
- you have a short trip with fixed dates
- you plan to see Ang Thong, which is closed until 15 December
Getting there: Bangkok to Koh Samui. The month after is Koh Samui in December.
FAQ
Is November rainy season on Koh Samui?
Yes, it is the peak. TMD 1991-2020 normals give 444.6 mm in November, 22% of Samui's yearly 1,994.3 mm, on 18.7 rainy days. October (294.9 mm) and December (263.1 mm) are also wet. Samui's rain comes with the northeast monsoon, so it peaks later in the year than on Phuket.
Does it rain all day on Samui in November?
Not every day, but the downpours can be heavy. The 18.7 rainy days include any day with 0.1 mm or more, and the wettest November day on record for 1991-2020 brought 363.9 mm. TMD's outlook for November 2026 warns of heavy to very heavy rain in places and possible flash floods.
Can you swim on Koh Samui in November?
On calm days, yes, but expect rough water. TMD's outlook gives the Gulf of Thailand waves of 2-4 m at times from mid-October to early January. The prevailing November wind on Samui is from the east, so the east coast beaches such as Chaweng and Lamai face it. Follow the beach flag and lifeguards.
Is Ang Thong Marine Park open in November?
No. The DNP closure table lists all tourist sites and accommodation in Mu Ko Ang Thong National Park as closed from 1 November to 15 December every year. The park reopens on 16 December.
Is Phuket better than Samui in November?
For dry weather, yes. TMD normals give Phuket 178.2 mm of rain in November against Samui's 444.6 mm, and Phuket's wind turns offshore on the west coast. The full monthly comparison is on Phuket or Koh Samui in November.
When is the best time to visit Koh Samui instead?
February to April: TMD normals give 64-116 mm a month and 5.6-8.1 rainy days. February is the driest month at 64.3 mm. December is still wet (263.1 mm), and January is a transition month (126.8 mm).
Sources
- TMD. Climatological Data of Thailand for 30 Year Period (1991-2020), Ko Samui (48 550), printed p. 71, and Phuket (48 564), printed p. 82
- TMD. Cool season outlook for Thailand 2026-2027, issued 9 October 2026 (Thai)
- TMD. Seasonal forecasts page (no update after 9 October as of 27 October 2026)
- TMD. 7-day weather forecast by region
- DNP. Opening and closing of tourism in national parks (closure table, data as of 7 January 2026)
- DNP. Entrance fees for individuals (CSV, edition of 2 June 2023)
- MOTS. Tourism statistics by province 2025, monthly sheets (xlsx)
- TAT Newsroom. Nakhon Phanom Illuminated Boat Procession 2026: end of Buddhist Lent on 26 October
Found an error or outdated fact? Tell the editors, we will fix it and update the check date.