Koh Samui weather October marks the start of the island's wet season. On 30-year averages the rain more than doubles compared with September, and October has more rainy days than any other month of the year.
This guide gives you the official numbers, explains how the sea changes as the monsoon turns, and shows how to plan an October trip, including the last weeks before Ang Thong Marine Park closes.
Koh Samui Weather October at a Glance
October is a transition month. Showers become frequent and longer, humidity rises and the wind starts to shift towards the northeast monsoon that dominates November and December.
- Rainfall
- 294.9 mm
- Rainy days
- 19.3
- Average high
- 30.6°C
- Average low
- 24.3°C
- Humidity
- 85%
- Wind
- 2.0 kn, west
These Koh Samui weather October figures are the 1991–2020 climate normals of the Thai Meteorological Department for its Ko Samui station. They describe a typical October, not a forecast for your dates, and one station stands for the whole island.
Good for
- Flexible travellers
- Quiet beaches and low-season rates
- Spa and food-focused trips
- Ang Thong before it closes on 1 November
Think twice if
- You need reliable beach weather
- Your trip is short
- Boat trips are the main reason for your visit
- You plan to ride a scooter every day
Where Koh Samui weather October sits in the year: average rainfall per month in millimetres, Thai Meteorological Department, Ko Samui station, 1991–2020. Select a month to open its guide.
Not sure October works for your trip?
Send us your dates and plans. A local will tell you honestly whether to keep them or shift them.
Koh Samui Weather October: Rain and Heat
The Thai Meteorological Department's Ko Samui station records an average of 294.9 mm of rain in October over 19.3 rainy days, the highest number of rainy days of any month. Only November gets more rain in total.
Showers become longer and heavier, and grey days are common. The average high is 30.6°C and the low 24.3°C, while humidity rises to 85%.
For your actual dates, rely on short-range forecasts. Our 14-day forecast guide shows where to look.
If a storm warning is issued
The Thai Meteorological Department issues warnings for heavy rain and strong waves. Our storm safety guide explains what to do.
Koh Samui Weather October: Sea Conditions and Swimming
On the station's 30-year records the prevailing wind in October is still westerly, with the lightest average speed of the year, 2.0 knots. Towards the end of the month the northeast monsoon begins to set in, and the east coast can become rougher.
Boat trips run on many days but are more likely to be postponed after storms. Visibility for snorkelling often drops after heavy rain.
Swimming safety
Lifeguard cover is limited on many Samui beaches. Stay out of the water when red flags are up or when waves break hard on the shore, keep children within reach, and ask your hotel about currents on the day. A calm-looking bay can still pull.
Koh Samui Weather October: Where to Stay
In a wetter month, choose a base where rainy afternoons are easy: walkable streets, cafés and spas.
| Area | Coast | In October |
|---|---|---|
| Chaweng | East | Everything on foot; sea can turn rough late in the month. |
| Bophut and Fisherman's Village | North | Walkable, cafés and shops. |
| Lamai | East | Lively, smaller than Chaweng. |
| Maenam | North | Quiet; fewer options in walking distance. |
| West coast | West | Sunsets and calm; you need transport. |
Bophut and Chaweng make rainy days easy; the west coast is lovely but quiet and more isolated. Compare every area in our where to stay in Koh Samui guide.
When you have narrowed it down, compare rooms for your exact dates on Agoda and read the cancellation terms of each rate before you pay: they differ from one offer to the next.
Koh Samui Weather October: Best Things to Do
October rewards a flexible mix of indoor and outdoor plans.
| Activity | In October | Plan B |
|---|---|---|
| Ang Thong Marine Park | Open until 31 October (2026 dates) | Pig Island on a calmer day |
| Boat trips | Run on many days, postponed after storms | Book early in your stay |
| Spa and massage | Unaffected | — |
| Cooking class | Indoors | — |
| Na Muang waterfall | Full flow, slippery | Skip after heavy rain |
If Ang Thong is on your list, book it early in October and early in your stay: in 2026 the park closed on 1 November.
A rainy-day list
Spa treatments, cooking classes, Muay Thai shows and the cafés of Fisherman's Village all work in the rain. Keep one outdoor plan per day and swap it when the sky clears.
Early or late October?
Monthly averages cannot tell you which half of October will be drier in your year. What is certain is the calendar: Ang Thong's season ended on 31 October in 2026, so early October gives you more chances to go.
Is October good for a long stay?
For remote workers and long-stay visitors, October can work well: rates are low and the island is quiet. Choose accommodation with backup power and reliable internet, since storms can cause short power cuts, and a walkable area so wet days do not leave you stuck.
What changes from October to November
October's rain usually comes in heavy showers with drier spells between them. As the northeast monsoon takes hold towards November, rain can become more prolonged and the east coast rougher. If your dates can move, the first half of October is generally the safer bet for sea days.
Day trips in October
Short trips are the safest choice this month. Pig Island and the islands off the south coast take less time at sea than a full Koh Tao day, and Koh Phangan is a short ferry ride away. Book them early in your stay and check the forecast the evening before.
Ang Thong National Marine Park: kayak and snorkel day trip
Book it early in October and early in your stay: the park closed for the season on 1 November 2026, and storms can cancel trips.
Check on the listing before you book
- Pickup area and departure pier
- What happens if the park closes for weather
- Whether the national park fee is included
Powered by GetYourGuide. Price, duration and availability depend on your date.
Koh Samui Weather October: Day Trips
Samui is the hub for day trips in the Gulf of Thailand. In October, the average wind at the Ko Samui station is 2.0 knots from the west, which decides how comfortable the crossings are. Shorter trips are the safer choice whenever the forecast is borderline.
| Trip | In October |
|---|---|
| Ang Thong Marine Park | Open until 31 October in 2026, then closed until mid-December. |
| Koh Phangan | Short crossing; delays possible in rough weather. |
| Koh Tao and Koh Nang Yuan | Long crossing, often rough; frequent postponements. |
| Pig Island and the southern islands | Short trips; still subject to sea conditions. |
Whatever the month, book day trips early in your stay so you can move them, and read each operator's weather and cancellation policy. Our guides to Ang Thong, getting to Koh Phangan and Koh Nang Yuan cover each trip in detail.
Koh Samui Weather October: Ang Thong's Last Weeks and the Monsoon
Ang Thong Marine Park closed for the season on 1 November 2026 and was scheduled to reopen on 16 December 2026, according to the Department of National Parks' 2026 list. The closure dates for the following years are published by the department, so check them before you book.October is therefore the last chance of the year for Ang Thong. Pick a calm morning and keep a spare day in case the trip is postponed.
The bigger change comes with the northeast monsoon, which usually sets in on the Gulf side from late October. Our November guide explains what follows.
Koh Samui Weather October: Who It Suits
October suits travellers who value quiet and price over sunshine.
- Couples on a spa break. Quiet resorts and treatments unaffected by rain.
- Budget travellers. Low season rates.
- Remote workers. Calm cafés; check backup power and internet.
- Families. Possible with a walkable base and indoor plans.
- Snorkellers. Hit or miss; go early in the month.
Koh Samui Weather October: A 5-Day Plan
A flexible plan with the sea trip first.
- Day 1. Arrive, settle into Bophut, dinner in Fisherman's Village.
- Day 2. Ang Thong day trip if the forecast is calm.
- Day 3. Spare day: rebook the boat trip or visit Big Buddha and Wat Plai Laem.
- Day 4. Cooking class and spa.
- Day 5. Beach morning if dry, Na Muang waterfall if it has not rained heavily.
Koh Samui Weather October: Prices and Crowds
October is low season. Rooms are generally easier to find and cheaper than in high season.
Compare live prices for your dates rather than relying on percentages quoted online.
Koh Samui Weather October: Packing and Getting Around
Pack for warm rain.
- A rain jacket or poncho
- Quick-dry clothes and sandals
- A dry bag
- Insect repellent
- A power bank
Roads are slippery after rain and some low roads can flood briefly. Taxis or a rented car are safer than a scooter in heavy rain. If you plan to ride, read our scooter rental guide first, and keep data on your phone with an eSIM for Thailand so you can check radar and messages on the road.
Koh Samui Weather October: Health and Safety
Temperatures in October are comfortable by tropical standards, with average highs of 30.6°C, but the sun is strong all year at this latitude. Use a hat and a high-factor sunscreen even on cloudy days, and drink plenty of water on boat trips.
Mosquito-borne illnesses such as dengue occur in Thailand all year and are more common in the rainy season. Use repellent, especially at dawn and dusk, and choose rooms with screens or air conditioning.
Wet roads are the biggest everyday risk. Helmets are compulsory for scooter riders in Thailand, and many accidents involving visitors happen on slippery roads after rain. If you are not an experienced rider, use taxis or a rented car.
Travel insurance that covers medical care and weather-related changes is worth having whatever the month.
Koh Samui Weather October: Getting Here
Most visitors arrive either by air into Samui's own airport, mainly with flights from Bangkok, or by flying or taking the train or bus to Surat Thani and crossing by ferry from Donsak to Nathon or Lipa Noi. The ferry route is usually cheaper and takes longer.
In the wetter months, ferries keep running on most days but can be delayed or cancelled when the Gulf is rough. Avoid tight connections, and keep a buffer day before an international flight.
Compare ferries and flights on 12Go for your dates, and see our Koh Samui ferry guide for the routes. Ferries run on most days but can be delayed or cancelled in rough weather.
Koh Samui Weather October: Booking Tips
- Read cancellation terms on each offer.
- Book Ang Thong and other sea trips early in your stay.
- Leave a buffer day before international flights.
- Check that your travel insurance covers weather-related changes.
Booking a few weeks ahead and reading the conditions of each rate matters more than chasing the lowest headline price.
Koh Samui Weather October vs September and November
| Month | Rainfall | Rainy days | High / low | Wind |
|---|---|---|---|---|
| September | 117.5 mm | 15.0 | 31.9°C / 24.8°C | 2.6 kn, west |
| October | 294.9 mm | 19.3 | 30.6°C / 24.3°C | 2.0 kn, west |
| November | 444.6 mm | 18.7 | 29.7°C / 24.1°C | 2.9 kn, east |
October has about two and a half times September's rain and the most rainy days of the year. November is wetter still in total, before the season eases in December. To weigh every month side by side, use our best time to visit Koh Samui guide.
The bottom line on Koh Samui weather October
October is the start of Samui's wet season, with the most rainy days of the year. Come with flexible plans, a walkable base and indoor options, and book Ang Thong early before the park's November closure.
Koh Samui Weather October: FAQ
Is October a good time to visit Koh Samui?
Only if you are flexible. Rain more than doubles compared with September, and October has the most rainy days of the year on average.
How much does it rain in Koh Samui in October?
The 1991–2020 average is 294.9 mm over 19.3 rainy days at the Thai Meteorological Department's Ko Samui station.
Is Ang Thong open in October?
Yes. In 2026 it closed on 1 November and was scheduled to reopen on 16 December.
Is October monsoon season on Koh Samui?
It is the start of the wet season. The heaviest rain usually falls in November.
Is October or September better?
September, on averages: 117.5 mm over 15 rainy days, against 294.9 mm over 19.3 days in October.
Will it rain every day in October?
Not every day, but October has the most rainy days of the year on average, 19.3.
Is October cheap on Koh Samui?
It is low season, so rates are generally lower than in high season. Compare live prices for your dates.
Planning an October trip?
Tell us your dates and what you want to do, and we will help you decide what to book now and what to keep flexible.
Compare with September or read our seasons guide for the full year.
Sources for Koh Samui Weather October
Climate figures on this page come from the Thai Meteorological Department's 30-year climate normals. Other facts were checked on 13 November 2026 against the sources below. Weather, park rules and event dates can change, so confirm locally before you travel.
- Thai Meteorological Department: climatological data for the period 1991–2020 (Ko Samui station 48550)
- Thai Meteorological Department: forecasts and warnings
- Tourism Authority of Thailand
- Asia Roamer: Ang Thong closure dates, citing the DNP 2026 list
- SB Excursion: Ang Thong closes 1 November to 15 December 2026
How we put this guide together
Every climate figure on this page comes from one official dataset, the Thai Meteorological Department's 1991–2020 normals for the Ko Samui station, so the October numbers can be compared fairly with every other month in our series. We do not publish rain probabilities by week, sunshine hours or sea temperatures, because no official Samui series supports them.
Dates for parks, festivals and holidays were checked against the sources listed above. Prices change daily, so we point you to live availability instead of quoting rates. We update this guide when an official date or rule changes.
Disclosure: InsideSamui may earn a commission when you book through some links on this page, at no extra cost to you. Tour listings are provided by GetYourGuide. Prices, park rules and event dates change, so always confirm before you travel.