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One of Thailand’s most popular island getaways, Koh Samui offers a bite-sized sample of everything that tourists love about Thailand. With idyllic shorelines, affordable spas, accessible hikes, fantastic street food and a great party scene, the island packs plenty of excitement and adventure into its humble confines.
Whether you want to party, chill or fill your days with endless outdoor adventures, you can do it all excellently and easily in Koh Samui.
But depending upon when you visit Koh Samui, your experience can vary hugely. With its tropical climate, extremely changeable weather and busy high tourist season, it’s essential to visit during a time which is perfect for you.
If you’re planning an exciting adventure, but you’re not sure exactly when you should travel to Koh Samui, we’ve got you covered.
We’ve compiled lots of useful information about events, weather and seasons in Koh Samui, so you’re armed with all the knowledge you need to book your trip for the perfect time.
So let’s dive in!
For those who don’t have much time, here’s our quick verdict…
We recommend traveling to Koh Samui during one of two separate periods:
Our first recommendation is to visit Koh Samui during the dry season, from December to March, when temperatures, rainfall and humidity are low. This is Koh Samui’s weather at its best, and it’s perfect for sunbathing, beaches, hiking, island-hopping and all the other adventures that Koh Samui has to offer.
Yes, this period is very busy with crowds of countless tourists, but don’t let that deter you.
Alternatively, you could travel slightly later in the year, during April’s Thai New Year celebrations of Songkran. One of the world’s most exciting and unusual festivals, Songkran is essentially a week-long water fight.
The Weather Seasons in Koh Samui
Because Koh Samui has a tropical climate, its year has three distinct seasons (rather than the four seasons which most tourists might be accustomed to). These three seasons are the dry season, the hot season and the rainy season.
Here’s a brief introduction to what these three different seasons offer:
1. Hot Season: April to August
Aptly named, this season is Koh Samui’s hottest, with soaring temperatures averaging around 32ºC, though highs are often even higher. Though these temperatures would typically be unpleasant and disruptive in a city, they can be tolerable in Koh Samui if your plans mainly include soaking up the sea.
That said, if you want to hike and enjoy other outdoor activities, the hot season isn’t the best time.
May is the hottest of all of Koh Samui’s month, and temperatures can begin to get a little uncomfortable for even the most sun-seeking of beach bums. That said, May is also the rainiest month, so there’s often some welcome respite from the sweltering heat.
Of all the months in this period, April offers the most pleasant weather, with little rain and slightly less humidity.
If possible, you should try to visit Koh Samui in April. Not only does it offer the best weather of all the months in this season, but it also plays host to Songkran. The Thai New Year, the entirety of Thailand is absolutely dominated by the huge celebrations, which take over the nation for around a week.
Songkran is essentially a giant water fight, and everyone in the entire nation gets involved. With buckets of ice, jugs of water and endless water pistols, it’s one of the world’s most fun festivals, with an unforgettable atmosphere. Loud music, smiling locals and painted faces complete the picture, for one of the most unusual experiences that world travel has to offer.
2. Rainy Season: September to November
Though this period is (no surprises here!) wet and humid, Koh Samui’s rainy season isn’t as disruptive as it can be in some other parts of Southeast Asia. It’s absolutely the least pleasant time to visit the area, but it’s not certainly not unbearable.
If you visit during this period, you’re very likely to experience some rain, but some days still bring the pleasant weather needed to enjoy the stunning shores of Koh Samui’s beaches. While November is very rainy, September is usually okay, with a relative lack of troublesome downpours.
During this period, Koh Samui has relatively few tourists, so it can be a great time to visit if you’re keen to avoid crowds.
A huge highlight of this season is the Loy Krathong lantern festival, which is a major tourist attraction. With thousands of illuminated lanterns floating on Koh Samui’s waters, it’s one of the best and most beautiful ways to experience the island.
3. Dry Season: December to March
Koh Samui’s most pleasant period, this season is typically also its busiest, with endless tourists flocking to the island to enjoy its beautiful weather. This season has little rain and relatively lower temperatures, with average climes of around 28ºC. The levels of humidity are also pretty manageable.
If you want to enjoy some outdoor adventures while you’re in Koh Samui, this is the best period to visit, perfect for hiking, swimming and sightseeing.
Some tourists don’t like to travel during this season as Koh Samui can be very busy. But though the crowds can be countless, you shouldn’t let that put you off.
If you want to experience Christmas and New Year’s in Thailand, Koh Samui is a fantastic destination for both. While the Christmas celebrations are fun but fairly low-key, Koh Samui embraces the western New Year with utter enthusiasm.
Koh Samui Weather Charts
Tourist Seasons in Koh Samui
1. High Season
High season in Koh Samui is the same as its dry season, from December to March. Because of the low rainfall, manageable humidity and pleasant temperatures, it’s the best time to enjoy Koh Samui’s diverse adventures and escapades.
Here are the best things to do in Koh Samui during the idyllic island’s high season:
- Christmas: though Christmas isn’t traditionally celebrated in Thailand, modern Thailand now welcomes the fun of the holiday season. Christmas in Koh Samui isn’t anything crazy, but it’s full of smiling faces, seasonal decorations and occasional Santa appearances.
- New Year’s: Thailand fully embraces the western New Year’s, and Koh Samui is one of the best places to experience it. With big parties, fantastic firework displays and great DJs, there’s lots of fun for travelers of all descriptions. Backpackers, couples and families can all find a great way to celebrate New Year’s on Koh Samui.
- Makha Bucha Day: one of Thailand’s biggest Buddhist festivals, Makha Bucha Day involves holy gatherings of monks along with tributes to Buddha. Though the celebrations in Koh Samui are quite small, they’re still a great insight into Thailand’s relationship with its main religion. This event typically occurs in February or March.
2. Low Season
Koh Samui’s low season is the same as its rainy season, from September to November, as many tourists stay away from the island in fear that the rain will disrupt their trip. But in truth, this isn’t a terrible time to visit Koh Samui, as crowds and prices are lower and the weather is usually pretty tolerable. The only month you should try to avoid is November, which is Koh Samui’s wettest.
If you decide to visit Koh Samui during this period, there are still some pretty interesting events. Here are our highlights:
- Loy Krathong: this light festival is one of Thailand’s most aesthetic celebrations. During this event, locals build small lotus-shaped floats and fill them with candles. These candles are placed in water, whether it’s the ocean, lakes or hotel swimming pools. Against the backdrop of the deep dark of Koh Samui’s nightfall, this is one of Thailand’s most beautiful sights. Loy Krathong typically takes place in November.
- Chulalongkorn Day: subtle and introspective, Chulalongkorn Day pays tribute to King Chulalongkorn.Though the events in other parts of Thailand are bigger, Koh Samui still pays its respects every October 23rd, with flowers, prayers and food.
3. Shoulder Season
Koh Samui’s shoulder season is the same as its hot season, from April to August. While some tourists avoid this period in an attempt to dodge Koh Samui’s sun at its most intense, others flock to the beaches to enjoy the heat.
Some highlights during this period include:
- Songkran: this is truly one of the world’s best parties. A seven-day water fight, it’s Thailand at its most fun, and Koh Samui embraces the celebrations more than many other parts of Thailand. If you like water fights or unusual events, you’ll love this.
- Visakha Bucha Day: one of Buddhism’s most important holidays, this May event features religious ceremonies, temple visits and small processions. This one day celebrates three things: Buddha’s birth, Buddha’s death and Buddha’s enlightenment.
- Koh Samui Regatta: one of the best sports events in the whole of Southeast Asia, Samui Regatta has been attracting boat fans to the island since 2002. For one full week in May, sailing ships race near the island in some of the best yachts you’ll have ever seen.
When to Visit Koh Samui – Depending on the Type of Traveller You Are
The Best Time to Visit Koh Samui for Shopping
Though Koh Samui has many great places to bag some bargains, it’s not traditionally a destination for travelers whose priority is shopping.
That said, if you do want to shop while you’re on the idyllic island of Koh Samui, the best period is during the dry season, from December to March. Temperatures and rainfall are at their lowest, making for prime shopping climes – no-one wants to shop when it’s hot, sweaty and humid.
The Best Time to Visit Koh Samui for a Honeymoon
Koh Samui is an incredible destination for a honeymoon. While it’s an absolute haven of an island escape, it also offers great conveniences, world-class food and lots of luxury for those who want it. With villas, private pools and lots of romantic hotels, you can visit Koh Samui without behaving like a budget backpacker.
But the best time to visit for a honeymoon depends upon your priorities as a couple. If you want to avoid crowds (and feel like you have small portions of the island to yourself), you should visit during the rainy season, when tourist numbers are low.
If you want to hike and sightsee, visit during the cool season.
If you want to lie back and relax to indulge yourself, the hot season is fine.
Think about what you want to do on your honeymoon, and plan your trip accordingly. At all times of year, Koh Samui can be a perfect romantic getaway.
The Best Time to Visit Koh Samui for Culture and Museums
People don’t typically visit Koh Samui for culture and museums. While the island is home to interesting attractions such as Wat Plai Laem, Wat Khunaram and Samui Art Museum, they aren’t the big attractions here.
So while cool season is the best time to enjoy temples, museums and other cultural attractions, we wouldn’t recommend that you base your trip around the prospect of visiting these places.
The Best Time for Sightseeing and Outdoor Activities in Koh Samui
We’ve said that people don’t visit Koh Samui for its indoor attractions. But they absolutely do visit for the island’s outdoor adventures.
But these fun outdoor activities aren’t all made equal. While lying lazily in the sun is one of Koh Samui’s biggest draws, more active travelers might prefer to hike, visit waterfalls, explore the jungle and take boat tours.
If you simply want to lap up the sun while you lay on Koh Samui’s golden shores, both the dry season and the warm season are great options. But if you want to indulge in some adventure travel, it’s better to travel during the dry season, when humidity and temperatures are lower. Though hiking, adventuring and jungle exploring are all perfectly possible in the hot season, they’re also very sticky and sweaty during this period, so they aren’t quite as pleasant.
The Best Time to Visit Koh Samui on a Budget
Year-round, Koh Samui is a very affordable destination, and you can enjoy its low prices anytime. That said, it’s not quite as inexpensive as most of Thailand’s mainland.
If you have a very tight budget and you really want to travel during Koh Samui’s most affordable period, plan your trip for the rainiest months of October and November, when rainfall is high and visitor numbers are relatively low.
During this period, you can get better deals on trips, accommodation and even food and drink.
The Best Time to Visit Koh Samui with Kids and Families
If you’re travelling with kids, it’s best to visit Koh Samui during the dry period, when temperatures, rainfall and humidity are low.
No-one wants to deal with complaining kids, and traveling during this period guarantees that you can have no weather-related whining (though we can’t guarantee there won’t be any other types of complaints).
Though Koh Samui is typically popular with backpackers and couples, the island also has lots of fun excitement and adventures for kids of all ages. Highlights include Aquapark Samui, Ang Thong Marine National Park and Samui Go-Kart.
The Best Time to Visit Koh Samui for Hiking
Without doubt, the best period for hiking in Koh Samui is during the dry season, when temperatures, rainfall and humidity are all low.
If you hike in Koh Samui at any other time of year, it might be too wet, hot or humid, all of which can be unpleasant.
The Best Time to Visit Koh Samui for Beaches, Swimming and Suntanning
Most months are pretty good. The only exception is November, when rainfall is very high. Though October, September and May are also pretty rainy, those months offer enough pleasant days to make shoreline lazing a possibility.
You should also think carefully about what you like to do on the beach. If it’s simply sitting around, the hot season is probably your best option. But if you like beach walks and a little more action and activity, you should visit during Koh Samui’s cool season.
The Best Time to Visit Koh Samui for Diving
Many travelers visit Koh Samui to dive near the island – and near Koh Phangan and Koh Tao. If that’s your plan, you can dive in the area 12 months of the year, but those who are particularly keen should visit outside of the rainy season, as monsoons can make visibility poor.
The absolute best time to dive, in terms of visibility, is between March and September, when visibility is up to an impressive 35m.
If you want to see whale sharks, visit during March, April, September or October, when they’re most prevalent in the area.
Best Time to Visit Koh Samui for Surfing
Surfing is popular in Koh Samui, and many small stores and shacks rent surfboards and bodyboards.
The best time of year for surfing is from October to December, with great surf and meter-high beach breaks. The best surfing spot on Koh Samui is Chaweng Beach. Though the swells can be great, you might have to wait a little while for them, as the waves are dictated only by the wind – there’s no groundswell on Koh Samui.
If you’re a first-timer, Koh Samui is a great pick for your first surfing experience, with very rideable waves and lots of friendly tourists and locals who’ll be happy to help you out.
Koh Samui Weather Month by Month
The western New Year kickstarts some of Koh Samui’s best weather. With average temperatures of around 28ºC, very little rainfall and pretty low humidity, this is Koh Samui at its best. Whether you want to hike, swim, sunbathe or island-hop, January is a fantastic time to do it all.
You should wear loose-fitting breathable clothing when you’re not at the beach.
January is also one of Koh Samui’s busiest months, as travelers from around the world come to the island to experience its great weather. Keep this in mind if you’re looking to avoid large groups of other tourists, though it rarely poses much of a problem.
Highlights in January include both the western New Year’s and Chinese New Year.
If you can visit Koh Samui during the turn of the western New Year’s, you’ll enjoy great parties and fantastic fireworks displays. If you prefer the Chinese New Year (which lands in January or February, depending on the year), you can enjoy temple celebrations, street events and special foods.
February on Koh Samui is pretty similar to January, though it’s even drier and a little hotter, with average temperatures of around 29ºC. Again, this is perfect weather for everything that Koh Samui has to offer, and is especially good for enjoying its beautiful beaches.
Again, this is a busy month, but you shouldn’t let that deter you unless you’re particularly averse to large groups of crowds.
In February, you can usually enjoy Makha Bucha Day (though it may occur in March depending on the year). One of the most important Buddhist festivals throughout the world, it includes processions, temple visits and religious services and ceremonies.
Though Makha Bucha Day celebrations are more significant in Thailand’s bigger destinations, they’re still interesting on Koh Samui, and they make the atmosphere even more laid-back.
The last month before what’s typically considered to be the onset of the hot season, March is again very dry. Though it’s not part of the hot season, temperatures in March do begin to creep up quite significantly, with average temperatures of around 31ºC.
You should ensure that you bring cool, breathable clothes for the moments when you’re not on the beach.
Though this is part of Koh Samui’s busy period, tourist numbers drop off a little, so it can be a good time to visit if you want to combine good weather with relatively fewer crowds.
Though there aren’t many events during March, Koh Samui likes any excuse for a party, so it fully embraces the excitement of St Patrick’s Day. The verdant island becomes even greener as Koh Samui celebrates the Irish festivities.
The beginning of Koh Samui’s hot season, you won’t be surprised to hear that temperatures increase once more in April. As average climes reach 32ºC, rain also becomes a little more prevalent, but it’s by no means a problem.
Though April is a little less busy than the months which make up peak season, tourist numbers are pretty high, as lots of travelers make their way to the island to enjoy the soggy celebrations of Songkran.
With loud music, countless water guns and ice-laden pickup trucks, Thailand hosts the world’s biggest water fight every single year. Though Songkran marks the Thai New Year, it’s now become so much more than that, and is an incredibly iconic celebration. On every corner, you’ll be squirted, splashed or soaked, as there’s no escape from the fun.
Though Songkran is disruptive, it’s one of the world’s most unforgettable experiences. Yes, any type of normal sightseeing is completely impossible during this period, but who needs normal sightseeing when you have the much more exciting Songkran?
May is Koh Samui’s hottest month, with soaring average temperatures of around 33ºC. It’s also pretty rainy.
You should pack very light clothing along with a good waterproof.
Though May’s weather isn’t great, there are relatively few tourists during this period, as Songkran’s crowds have dissipated, and lots of tourists stay away to avoid the scathing heat. If you’re keen to avoid crowds, May is a decent time to do it without having to endure the potentially-heavy monsoons of Koh Samui’s rainy season.
May is Koh Samui’s sportiest month, with the yacht-filled Samui Regatta along with Koh Samui Bike Week, a roaring celebration of revving engines and soaring speeds. If you like journeys either overland or on sea, it’s a great time to visit Koh Samui.
June is significantly drier and slightly cooler than May, with average temperatures of around 32ºC.
Though the rain drops off a little, the humidity is still pretty high, so make sure you have breathable clothing. If you’re a particularly sweaty person, you might want to avoid June and the other months in this period.
In June, there aren’t many huge events, so it can be a good time to visit if you want to enjoy Koh Samui while it’s relatively quiet and calm.
July is the heart of Koh Samui’s hot season, as average temperatures sit at around 32ºC and rainfall is moderately high. Hot, humid and rainy, it’s not Koh Samui’s most comfortable month, but there are still some pretty good periods of beach-friendly weather.
You should pack a breathable, waterproof coat, as you’ll likely experience both sweats and showers.
July usually hosts Asahna Bucha Day, a Buddhist holiday which commemorates Buddha’s first sermon. Though celebrations in Koh Samui aren’t huge, they feature temple visits, small religious ceremonies and the giving of flowers.
The final month of Koh Samui’s hot season, high temperatures continue into August, with averages of around 32ºC. Rain decreases from the moderate rainfall of July for a relatively dry month in August, though humidity remains high.
Though this month isn’t perfect for outdoor adventuring, it’s better than the 2-3 months which precede it.
Though you might not need it, you should still pack a waterproof coat.
Cultural highlights during August include the Queen’s Birthday. Though this day marks the birthday of Queen Sirikit, it also doubles up as Mother’s Day, making for a pretty important day in the Thai calendar. Celebrations are pretty humble on Koh Samui, but there may be some small candle-lit illuminations.
Though September is the beginning of Koh Samui’s wet season, it’s relatively pretty dry, with an average of 11 rainy days. Temperatures sit at an average of around 31ºC and humidity is pretty high.
It’s still an okay time for some shoreline chilling, but it’s not ideal for other outdoor adventures, such as hiking and jungle exploring.
If you want to enjoy decent beach weather without too many crowds, September can be a good choice, as many tourists stay away in fear of disruptive rain. A lack of events also leads to a relative lack of crowds, making September a great month for those who like a little more solitude and serenity.
During October, the rainy season begins to take hold of Koh Samui, as disruptive downpours increase fairly significantly. Around half of Koh Samui’s October days include some rain. Humidity drops a little, and average temperatures sit at around 29ºC.
If you’re visiting Koh Samui in October, you should definitely pack some waterproof clothing for any hiking or jungle exploring.
Though October isn’t a great time to visit Koh Samui, it can be a good time for avoiding crowds. And while rainfall is overall pretty high, you should still get some decent beach weather during the breaks in the downpours. If you’re very lucky, these breaks can be several days long.
Koh Samui’s October highlights include Chulalongkorn Day and Halloween. Though Halloween isn’t a traditional Thai holiday, many hotels, hostels and bars celebrate the occasion with parties, events and decorations.
Koh Samui’s rainiest month by far, November is the worst time to visit the island. Though good beach weather is still a possibility, it’s relatively unlikely, as more than half of November’s days are rainy. November in Koh Samui isn’t too humid, and temperatures drop a little, to averages sitting at around 28ºC.
If you’re in Koh Samui during November, you’ll absolutely need some good waterproof clothing.
Because November is Koh Samui’s rainiest month, it’s also typically its least busy, perfect if you want to grab some bargains (and don’t mind enduring some rain to get them).
November is typically home to the illumination extravaganza of Loy Krathong festival, one of the most beautiful occasions that Thailand has to offer. Koh Samui is one of the best places to experience it.
The beginning of Koh Samui’s fantastic dry season, December can occasionally be a little wet, but it’s way drier than November. Koh Samui’s coolest month, December temperatures sit at an average of around 27ºC.
If you want to enjoy the dry season before the crowds really begin to descend upon the island, early December is a great choice, though it comes with the small risk of some rain. From mid-December onwards, the island becomes very busy all the way until the end of the dry season.
Because of its cool temperatures, December on Koh Samui is great for hiking, jungle exploring and other outdoor activities.
December on Koh Samui can be very fun, as the island celebrates both Christmas and the western New Year’s. If you’ve ever dreamed of enjoying the festive period on a sunny Thai beach, Koh Samui is a brilliant place to do it.
Koh Samui is one of the most beautiful and exciting islands in the whole of Southeast Asia. And it’s not just a beach getaway. Though it offers some of Thailand’s best beaches, it also has great jungles, excellent hikes, fun parties and fantastic food.
But depending on when you visit Koh Samui, your trip can hugely differ. Because the island has three very different seasons, different types of year offer different experiences.
We recommend two separate periods:
If you want to experience the best of Koh Samui’s weather, visit during the dry season from December to March, when temperatures, rainfall and humidity are at their lowest. The weather during this period is great for hiking, exploring and sunbathing, so it’s a perfect time to visit the island.
If you’re interested in cultural experiences, you should instead visit Koh Samui in April, just after the end of the dry season. During April, the entirety of Thailand plays host to Songkran, the Thai New Year. Essentially a week-long country-wide water fight, it truly is one of the best cultural experiences in the world – and Koh Samui is one of the best places to experience it.
But whenever you visit Koh Samui, you’ll have an excellent time. Packed with dense jungles, easy hikes, soothing shores and great opportunities for island-hopping, it’s one of Thailand’s most exciting destinations.
Paul is a handsome and hilarious travel writer and travel journalist from the UK. He’s hiked, hitchhiked and laughed his way through more than fifty countries, and he’s always looking for a new place to call home. Originally from Newcastle, he’s lived all over the UK, spent more than three years in Asia, and most recently lived in Vietnam. Here’s his website.