Koh Samui weather March combines two things travellers want: very few rainy days and a sea that is often calmer than in January and February, because the wind starts to ease. The trade-off is heat, which builds through the month towards the hottest season of the year.
This guide gives you the official averages, explains the one quirk in March's rain figures, and shows why it is one of the best months for boat trips and snorkelling.
Koh Samui Weather March at a Glance
March is still dry season. Rain falls on about six days in an average year, the wind is lighter than in February, and temperatures rise. It is one of the most reliable months for sea trips.
- Rainfall
- 115.8 mm
- Rainy days
- 5.9
- Average high
- 30.4°C
- Average low
- 25.4°C
- Humidity
- 81%
- Wind
- 4.1 kn, southeast
These Koh Samui weather March figures are the 1991–2020 climate normals of the Thai Meteorological Department for its Ko Samui station. They describe a typical March, not a forecast for your dates, and one station stands for the whole island.
Good for
- Boat trips and snorkelling
- Beach holidays with fewer crowds than February
- Couples and families
- Photographers who want clear days
Think twice if
- You struggle in heat
- You want the very lowest rain risk (choose February)
- You need guaranteed calm water every day
- You want low-season prices
Where Koh Samui weather March 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.
March is a sweet spot
Dry weather with less wind than February. Compare rooms for your dates and read each rate's cancellation terms.
Koh Samui Weather March: Rain and Heat
The Thai Meteorological Department's Ko Samui station records an average of 115.8 mm of rain in March, but over only 5.9 rainy days. That mix of few wet days and a fairly high total suggests rare but heavy downpours rather than regular showers; a handful of very wet years can also pull a 30-year average up.
In other words, expect mostly dry, sunny days, and treat a heavy downpour as possible but unusual.
Heat builds through the month. The average high is 30.4°C and the low 25.4°C, with humidity around 81%. Midday sun is strong, so plan beach time for mornings and late afternoons.
Koh Samui Weather March: Sea Conditions and Swimming
The average wind drops to 4.1 knots in March, still mostly from the southeast. That means fewer choppy days than in February and calmer crossings for boat trips, though a breezy day can still stir up the east coast.
On calm days the water is clear and warm, which makes March a good month to snorkel around Ang Thong, Koh Tao and the north coast. Our snorkelling and diving guide lists the main spots.
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 March: Where to Stay
In March, most coasts work. Choose by style: lively in Chaweng, walkable and calm in Bophut, quiet in Maenam and on the west coast.
| Area | Coast | In March |
|---|---|---|
| Chaweng | East | Lively, best choice of restaurants; occasional chop. |
| Bophut and Fisherman's Village | North | Walkable, calm water, good for families. |
| Maenam | North | Quiet, shallow, calm. |
| Lamai | East | Relaxed alternative to Chaweng. |
| West coast | West | Very calm, sunsets, quiet; transport needed. |
If heat bothers you, a room with good air conditioning and a pool matters more this month than in January. 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 March: Best Things to Do
March is one of the best months for getting out on the water, and the dry weather suits hiking and viewpoints too, as long as you start early.
| Activity | In March | Plan B |
|---|---|---|
| Ang Thong Marine Park | Open; often calm | Rebook if the operator postpones |
| Snorkelling | Clear water on calm days | North-coast spots on breezy days |
| Koh Tao and Koh Nang Yuan | Good conditions on calm days | Shorter trips to Pig Island |
| Viewpoints and hikes | Dry trails | Go early; it gets hot by late morning |
| Na Muang waterfall | Lower flow than in the wet season | Visit after a recent rain if you can |
Book sea trips for the morning when the light is good and the wind is usually lighter.
Beating the heat
Do outdoor sightseeing before 10 am and after 4 pm, and keep the middle of the day for the pool, a long lunch or a massage. Temples such as Big Buddha and Wat Plai Laem have little shade, so go early.
Clear-water days
The clearest water usually follows several calm days in a row. If the wind has been up, give it a day before booking a snorkelling trip, and ask the operator which sites they choose in the conditions.
Is March good for a first visit?
Yes. It combines dry weather, long days, mostly calm seas and full access to the island's activities, without the peak demand of January and February. If you are unsure which month to choose for a first trip, March is one of the safest bets, as long as you are comfortable in heat above 30°C. Families with young children should plan a slower pace around the middle of the day.
Sunsets and evenings
Clear skies in March make for long, colourful sunsets on the west coast around Lipa Noi and Taling Ngam, and over the sea from the north coast. Evenings are warm, so outdoor dinners on the beach are comfortable. Fisherman's Village in Bophut is busy and lively at night, with its walking street market on Fridays.
Ang Thong National Marine Park: kayak and snorkel day trip
March's calmer seas make it one of the best months for this day out. Morning departures usually have the lightest wind.
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 March: Day Trips
Samui is the hub for day trips in the Gulf of Thailand. In March, the average wind at the Ko Samui station is 4.1 knots from the southeast, which decides how comfortable the crossings are. Shorter trips are the safer choice whenever the forecast is borderline.
| Trip | In March |
|---|---|
| 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 March: The Best Month for Boat Trips?
On the numbers, March is among the strongest months for time on the water: few rainy days, lighter wind than January and February, and long sunny spells. February is drier but windier; April is calmer still but hotter and busier around Songkran.
That does not guarantee a calm sea on your chosen day. Operators decide on the morning, and the national parks department can close Ang Thong at short notice when waves are high. Keep a spare day in your plan.
For a first island day, Ang Thong is the classic choice. Read our Ang Thong guide and our island-hopping guide to compare routes.
Koh Samui Weather March: Who It Suits
March suits most travellers, especially those who want time at sea.
- Snorkellers and divers. Clear, calmer water on many days.
- Families. Dry weather and calm north-coast beaches; plan around the midday heat.
- Couples. Quieter than February with similar weather.
- Budget travellers. Still high season, but often easier to book than January and February.
- Hikers. Dry trails, best before 10 am.
Koh Samui Weather March: A 5-Day Plan
A plan built around morning sea time and early sightseeing.
- Day 1. Arrive, swim at Bophut or Maenam, dinner in Fisherman's Village.
- Day 2. Ang Thong day trip.
- Day 3. Big Buddha and Wat Plai Laem early; pool or beach in the afternoon.
- Day 4. Koh Tao and Koh Nang Yuan if calm, or Pig Island.
- Day 5. Viewpoint hike early, then Lamai and a sunset on the west coast.
Koh Samui Weather March: Prices and Crowds
March is still high season, but demand usually eases compared with January and February, and it is often easier to find a room.
Rates change daily, so compare live prices for your dates rather than relying on figures quoted online.
Koh Samui Weather March: Packing and Getting Around
Pack for heat and time on the water.
- Reef-safe mineral sunscreen and a rash guard
- A wide-brimmed hat
- A refillable water bottle
- Seasickness tablets for long crossings
- A dry bag
Roads are dry. Midday heat makes walking tiring, so plan short hops by taxi or ride-hailing app, and drink plenty of water if you ride a scooter. 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 March: Health and Safety
Heat is the main health risk in March, with average highs of 30.4°C and humidity around 81%. Drink water before you feel thirsty, add electrolytes on long days out, and keep the hours between 11 am and 3 pm for shade, the pool or a long lunch.
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 March: 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.
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. Sea crossings are usually smoother than in January and February.
Koh Samui Weather March: Booking Tips
- Book sea trips early in your stay and for the morning.
- Read the cancellation and weather policy of each tour.
- Choose a room with reliable air conditioning.
- Leave a buffer day before international flights.
Booking a few weeks ahead and reading the conditions of each rate matters more than chasing the lowest headline price.
Koh Samui Weather March vs February and April
| Month | Rainfall | Rainy days | High / low | Wind |
|---|---|---|---|---|
| February | 64.3 mm | 5.6 | 29.4°C / 24.9°C | 5.0 kn, southeast |
| March | 115.8 mm | 5.9 | 30.4°C / 25.4°C | 4.1 kn, southeast |
| April | 82.9 mm | 8.1 | 31.8°C / 26.0°C | 2.6 kn, east |
March has almost as few rainy days as February, lighter wind, and more heat. April is calmer and hotter still, and busy around Songkran. To weigh every month side by side, use our best time to visit Koh Samui guide.
The bottom line on Koh Samui weather March
March is one of the best all-round months on Samui: few rainy days, lighter wind than February and good conditions for boat trips. Plan around the heat and keep a spare day for sea trips.
Koh Samui Weather March: FAQ
Is March a good time to visit Koh Samui?
Yes. It has about six rainy days on average, lighter wind than February and long sunny spells. The main drawback is rising heat.
How much does it rain in Koh Samui in March?
The 1991–2020 average is 115.8 mm over 5.9 rainy days at the Thai Meteorological Department's Ko Samui station, which points to rare but heavy downpours.
Is March good for snorkelling?
Often, yes. Lighter wind and dry weather mean clear water on many days. Visibility still depends on recent wind and rain.
How hot is Koh Samui in March?
The average high is 30.4°C and the average low 25.4°C. The midday sun is strong.
Is Ang Thong open in March?
Yes, outside the annual closure period. It can still close at short notice when waves are high.
Is March busy on Koh Samui?
It is still high season, but usually less busy than January and February.
What is the sea temperature in March?
There is no official sea-temperature series for Samui from the Thai Meteorological Department; the water is warm all year, so no wetsuit is needed for swimming.
Planning March?
Compare rooms for your exact dates. Questions about coasts or boat trips? Ask a local on WhatsApp from the menu.
Next, see how April compares in our April guide, or step back to February.
Sources for Koh Samui Weather March
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
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 March 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.