Koh Samui weather January is one of the main reasons the island fills up after New Year. Rain is far less frequent than in November and December, nights are the mildest of the year, and most days are made for the beach. It is not the driest month, though, and a steady easterly wind can make the sea choppy on the east coast.
This guide gives you the 30-year averages, explains which side of the island to pick on a windy day, and shows how to book a peak-season stay without overpaying.
Koh Samui Weather January at a Glance
January is high season. Rain falls on about 11 days in an average year, usually in short showers, and the wind blows mostly from the east, which is what you need to plan your beach days around.
- Rainfall
- 126.8 mm
- Rainy days
- 11.1
- Average high
- 29.0°C
- Average low
- 24.2°C
- Humidity
- 83%
- Wind
- 4.5 kn, east
These Koh Samui weather January figures are the 1991–2020 climate normals of the Thai Meteorological Department for its Ko Samui station. They describe a typical January, not a forecast for your dates, and one station stands for the whole island.
Good for
- Beach holidays and sunshine
- Island trips, including Ang Thong
- Escaping the European winter
- Families after the New Year rush
Think twice if
- You want the driest month (that is February)
- You need a calm east-coast swim every day
- You are booking late for the first week
- You are on a tight budget
Where Koh Samui weather January 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.
January is high season
The best-located rooms go early. Compare what is still available for your dates, and check each rate's cancellation terms.
Koh Samui Weather January: Rain and Heat
The Thai Meteorological Department's Ko Samui station records an average of 126.8 mm of rain in January over 11.1 rainy days. That is less than half of December's total and about 40% fewer rainy days than November. Showers tend to be short, and many days are dry.
Temperatures are among the mildest of the year, with an average high of 29.0°C and a low of 24.2°C. Humidity averages 83%.
January is not bone dry, despite what many brochures say. If a few wet days would ruin your trip, February is the safer bet on averages.
Koh Samui Weather January: Sea Conditions and Swimming
Wind is the thing to plan for. January and February have the highest average wind speeds of the year at the Ko Samui station, 4.5 knots in January, blowing mostly from the east. Those winds bring waves to east-facing beaches and can make boat crossings bumpy.
On a windy day, Chaweng and Lamai get the most surf. Beaches on the north and west coasts, such as Bophut, Maenam and Lipa Noi, are usually more sheltered from an easterly wind. Compare them in our best beaches in Koh Samui guide.
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 January: Where to Stay
In January, the wind direction decides which beach is calm, so a base with easy access to both the east and north coasts gives you the most options.
| Area | Coast | In January |
|---|---|---|
| Chaweng | East | Busiest beach and nightlife; livelier surf on windy days. |
| Bophut and Maenam | North | Generally calmer water with an easterly wind; good for families. |
| Choeng Mon | North-east | Sheltered bays close to Chaweng. |
| Lamai | East | Slightly quieter than Chaweng; east-facing. |
| West coast | West | Quiet, sunsets, sheltered from easterly winds; you need transport. |
Families often prefer the calmer water of the north coast; travellers who want nightlife choose Chaweng and accept a livelier sea. 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 January: Best Things to Do
January is a good month for sea trips, as long as you accept that an operator may postpone on a windy day. The national parks department can close Ang Thong at short notice in rough seas, and local media reported a short closure of that kind in early January 2026.
| Activity | In January | Plan B |
|---|---|---|
| Ang Thong Marine Park | Open, weather permitting | Rebook on a calmer day |
| Pig Island and island-hopping | Usually running | Big Buddha, temples, viewpoints |
| Koh Tao day trip | Longer crossing, more affected by wind | Choose a trip closer to Samui |
| Beaches | Good on most days | Switch coast with the wind |
| Snorkelling | Depends on wind and recent rain | Try sheltered north-coast spots |
Book sea trips early in your stay so you have spare days to rebook. More options are in our Koh Samui boat trips and island-hopping guides.
Picking the right beach on a windy day
Check the wind direction in the morning. With a moderate east or southeast wind, north-coast beaches such as Bophut, Maenam and Bang Po are usually the calmest, and the west coast around Lipa Noi is flat and shallow. Chaweng and Lamai are better for watching waves than swimming on those days.
Snorkelling in January
Visibility depends on wind and recent rain rather than the calendar. Calm spells give the best chance of clear water around Ang Thong and Koh Tao; after a windy few days, expect stirred-up water close to shore. Our snorkelling and diving guide lists the main spots.
Ang Thong National Marine Park: kayak and snorkel day trip
The classic day out from Samui: limestone islands, a viewpoint climb and time in the water.
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 January: Day Trips
Samui is the hub for day trips in the Gulf of Thailand. In January, the average wind at the Ko Samui station is 4.5 knots from the east, which decides how comfortable the crossings are. Shorter trips are the safer choice whenever the forecast is borderline.
| Trip | In January |
|---|---|
| Ang Thong Marine Park | Open outside the annual closure; can close for a day in rough seas. |
| Koh Phangan | Short, usually smooth crossing. |
| Koh Tao and Koh Nang Yuan | Clear water, but the long crossing is affected by the strong winds of this season. Pick a calm day. |
| Pig Island and the southern islands | Short trips, the easiest choice on a borderline day. |
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 January: The Easterly Wind and Boat Days
Most of what goes wrong in a January holiday on Samui is not rain but wind. A few breezy days in a row stir up the east coast, make speedboat crossings uncomfortable and lead operators to postpone trips.
Two habits help. Check the wind forecast, not just rain, the evening before a boat trip, and keep your first two or three days for sea activities so you can move them. If you are prone to seasickness, choose a larger boat or a shorter crossing such as Pig Island over a long run to Koh Tao.
Long crossings are the most affected. Our Koh Nang Yuan guide explains what a Koh Tao day involves if you still want to go.
Koh Samui Weather January: Who It Suits
January suits almost everyone, as long as you book early.
- Families. Calm north-coast beaches and plenty to do; avoid the busiest first week if you can.
- Couples. Great beach weather and sunsets on the west coast.
- Divers and snorkellers. Good on calm days; Koh Tao trips depend on the wind.
- Budget travellers. High season prices; consider February or March for better value.
- Remote workers. Pleasant temperatures and steady routines; book long stays early.
Koh Samui Weather January: A 5-Day Plan
A plan that puts sea days first and keeps a spare day for wind.
- Day 1. Arrive, beach afternoon on the north coast.
- Day 2. Ang Thong day trip if the sea is calm.
- Day 3. Spare day for rebooking, or Big Buddha, Wat Plai Laem and a market dinner.
- Day 4. Pig Island or a snorkelling trip; afternoon at the beach.
- Day 5. Lamai and the Hin Ta Hin Yai rocks, then a sunset on the west coast.
Koh Samui Weather January: Prices and Crowds
January is high season, especially the first week after New Year. Expect higher room rates and fuller restaurants than in the green season.
Rates change daily, so compare live prices for your exact dates rather than relying on published percentages. The second half of the month is often easier to book than the first.
Koh Samui Weather January: Packing and Getting Around
Pack for sun and the occasional shower.
- Reef-safe mineral sunscreen, hat and sunglasses
- A light rain layer
- Seasickness tablets for boat days
- A dry bag
- Water shoes for rocky beaches
Roads are dry most days. If you rent a scooter, wear a helmet and avoid riding at night after drinks; taxis and ride-hailing apps cover the main beaches. 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 January: Health and Safety
Temperatures in January are comfortable by tropical standards, with average highs of 29.0°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.
Mosquitoes are fewer in the dry season but never absent. A repellent for dawn and dusk is still worth packing.
Helmets are compulsory for scooter riders in Thailand, and road accidents are the most common cause of serious injury for visitors. Ride slowly, avoid riding after drinking, and make sure your travel insurance covers scooters if you plan to ride.
Travel insurance that covers medical care and weather-related changes is worth having whatever the month.
Koh Samui Weather January: 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.
January includes the first week after New Year, one of the busier travel periods, so book flights and ferry transfers early.
Crossings can be bumpy on windy days. Larger car ferries are steadier than fast boats if you are prone to seasickness.
Compare ferries and flights on 12Go for your dates, and see our Koh Samui ferry guide for the routes. Crossings to Koh Phangan and Koh Tao can be bumpy on windy days.
Koh Samui Weather January: Booking Tips
- Book rooms and flights early, especially for the first week of January.
- Read the cancellation terms on each offer; they vary by room and rate.
- Plan sea trips early in your stay.
- Leave a buffer before onward ferries and flights.
Booking a few weeks ahead and reading the conditions of each rate matters more than chasing the lowest headline price.
Koh Samui Weather January vs December and February
| Month | Rainfall | Rainy days | High / low | Wind |
|---|---|---|---|---|
| December | 263.1 mm | 14.2 | 29.3°C / 24.0°C | 3.5 kn, northeast to east |
| January | 126.8 mm | 11.1 | 29.0°C / 24.2°C | 4.5 kn, east |
| February | 64.3 mm | 5.6 | 29.4°C / 24.9°C | 5.0 kn, southeast |
January sits between December, which is still wet, and February, the driest month of the year. It is also the second windiest month on average, after February. To weigh every month side by side, use our best time to visit Koh Samui guide.
The bottom line on Koh Samui weather January
January is high season for good reason: fewer rainy days, mild temperatures and beach weather most of the time. Plan around the easterly wind, put boat trips early in your stay, and book rooms well ahead, especially for the first week after New Year.
Koh Samui Weather January: FAQ
Is January a good time to visit Koh Samui?
Yes for most travellers. Rain is far less frequent than in November and December, temperatures are mild, and the beaches are at their best. Expect some showers and windy days on the east coast.
Does it rain in Koh Samui in January?
Some. The 1991–2020 average is 126.8 mm over 11.1 rainy days at the Thai Meteorological Department's Ko Samui station.
Is the sea rough in January?
It can be on the east coast when the easterly wind is strong. North and west-facing beaches are usually calmer on those days.
Is Ang Thong open in January?
It is outside the annual closure period, but the park can close for a day or two at short notice in rough seas. Your operator confirms the day before.
Is January or February better for Koh Samui?
On averages, February is drier: 64.3 mm over 5.6 rainy days, against 126.8 mm over 11.1 days in January. Both are windy on the east coast.
Is January crowded on Koh Samui?
The first week after New Year is one of the busiest of the year. The second half of the month is usually easier to book.
What should I pack for Koh Samui in January?
Light summer clothes, reef-safe sunscreen, a hat, a light rain layer and seasickness tablets for boat days.
Found your January dates?
Compare available rooms now. Unsure which area suits you? Ask a local on WhatsApp from the menu.
Comparing the high-season months? Read our February guide next.
Sources for Koh Samui Weather January
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 (checked 17 Oct 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 January 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.