Koh Samui
April 16, 2024

When's the best time to visit Koh Samui?

Let me guess: your beach holiday requires Koh Samui’s best time of year: the most sunshine, least cloud cover and fewest possible drops of rain? No problem.


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When’s the best time to visit Koh Samui?

So you want me to take away the guesswork and tell you when is the best time to visit Koh Samui? That's a little like asking someone to choose a favourite child: every month has something to recommend it. Here's exactly what you need to know about Koh Samui's weather, rain, clouds and climate– easily find out when is the best time for you to visit Koh Samui, using averages, anecdotes... and at least two Jurassic Park references.

Let me guess: your beach holiday requires Koh Samui’s best time of year: the most sunshine, least cloud cover and fewest possible drops of rain? No problem. And did you want pretty pictures instead of tedious charts? Done.

What do I know? For your anecdotal reference, I've tried and tested every month of Koh Samui's climate over the past twenty years. I’ve researched and written The Koh Samui Guide for ten years – truly the guidebook I’d give my very best friends. For statistical precision, I've spent quality time with eight years of Koh Samui weather averages and a spreadsheet. As such, I can hereby suggest when is best (weather-wise) to visit Koh Samui.

What’s the weather like on Koh Samui?

When's the Best Time to Visit Koh Samui?
Casa de Mar, a boutique hotel on Chaweng Beach, in March

For the most part, Koh Samui weather is hot and sunny – just what you want for a perfect beach holiday. There are two stark exceptions, as well as shoulder seasons, freak acts from the weather gods and, often, a delightfully cooling afternoon downpour. (Hey, it’s the tropics!) First up, are two stark exceptions to the “hot and sunny rule”

1. Rainy season

Koh Samui's rainy season is typically late October to mid-December. The average November rainfall on Koh Samui is 1.6 feet of rain. Yes, FEET. When it rains, it pours.

2. When it's *really* hot and sunny

That would be Koh Samui in April (with Songkran – the water festival – right in the middle).

Tip: Learn what to wear in Thailand to stay cool (and un-burnt).

My best advice about Koh Samui’s weather

When's the Best Time to Visit Koh Samui?
New Year's Day on Koh Samui (the exact same palm tree as the top photo – here in early January and above in late August)

1. Official party line

My official party line is that there's always a nice day to be had on Koh Samui; there's tons to do on rainy days.

2. Ignore the whingers

Every travel forum has a Barry-from-Blackpool who was dealt some bad luck when he vacationed at a time of year guaranteed to be sunny. January 2017 dealt the island some particularly memorable weather tricks. Sorry to say that’s just the nature of long-haul destinations in the tropics. You commit to dates far in advance and this lush corner of the world can offer some dramatic 'meteorological experiences'. But guess what? From a covered balcony, or room with a view, tropical storms are amazing. (See where to stay on Koh Samui).

3. Do this not that

Instead of allowing yourself to get weather-obsessed, I recommend you book your Koh Samui vacation when it's most convenient – when you most need days of perfect relaxation. Rest assured if it does decide to pour – any day of the year – there’s still plenty to do (rain or shine The Koh Samui Guide will easily keep you busy).

4. Sun-tanners – skip November

If you’re seeking assurance you’ll get a gorgeous, sunny Thai holiday and return home with a tan, then just about any month besides November will do its very best. November, Koh Samui’s wettest month, sees an average of 489.66 mm/10 inches of rainfall.

Tip: If you burn easily, avoid the sun, or don't like to tan, you might love visiting Koh Samui in November. For one thing, we get the island absolutely to ourselves and hotel rates are cheapy-cheap.

Your Koh Samui weather questions

When's the Best Time to Visit Koh Samui?
Chaweng Beach in September – a month that's "supposed to be" nice. (Expect rain in any month and plan to enjoy your vacation in any weather).

When is Koh Samui’s rainy/monsoon season?

Usually October through December – here's absolutely everything you need to know about Koh Samui's rainy season. Again, note that this timing is different from Phuket and other parts of Thailand.

When is the sunniest time of year on Koh Samui?

Defined by the fewest rainy days and the least median cloud cover, February and March are – statistically – the sunniest months. While superlatives are handy references, it’s a hair-splitting difference between “sunniest” and most of the rest of the year. Rather than four seasons, Koh Samui has two: lots of gorgeous weather, and a shorter rainy season.

Gauging the sunniest time on Koh Samui is more of a choose-your-own-adventure of plotting your favourite temperature against the potential for raindrops and cloud cover. If we take 'sunniest' to mean 'least median cloud cover', then it's February/March on Koh Samui (and the cloudiest time is September/October). But – as with weather everywhere – averages aren’t guarantees.

When's the Best Time to Visit Koh Samui?
A perfect September sky – statistically a cloudy month on Koh Samui. See how you can drive yourself crazy choosing "the best" weather?

Does March’s most-sunny designation make it the best time to visit Koh Samui? Not at all. I'm not certain what counts for ‘cloud cover’ in meteorological terms, and whether or not it would include any pretty wispy whites. Compare a few picture-postcard beach days at other times of the year. In all probability, they’re designated “partly cloudy”. Fine by me, how about you?

When is the driest time of year on Koh Samui?

Typically February is your best bet, with just 12% of the average rain seen in November. In second and third place for those of you avoiding puddles: March and April tend to be nice and dry, too (that is – unless you're visiting during Songkran. The weather might be dry but you won't be).

When is the hottest time of year on Koh Samui?

April (usually right around Songkran).

When's the Best Time to Visit Koh Samui?
A January sunset at Melati Beach Resort & Spa

When is the coolest time of year on Koh Samui?

January (statistically right after the New Year's Eve bustle).

Koh Samui weather by month

Here are my best answers to the question: “I’m coming to Koh Samui in [month]. What will the weather be like?” I both caution and cover my rear with this caveat: there’s no guarantee and this is a crazy world.


When's the Best Time to Visit Koh Samui?
Maenam Beach in January

One of the cooler months of the year on Koh Samui, with lows dipping to a ‘frigid’ 24.1°C (75°F). Coming from the tail-end of rainy season, the temperature heats up through the month. If you don’t like strong heat, a New Year trip to Koh Samui would suit you well.


When's the Best Time to Visit Koh Samui?
Big Buddha in February

Hey, guess what, it’s hot and sunny. February is an average of 1 degree Celsius hotter than January, with the lightest rainfall of any month.


When's the Best Time to Visit Koh Samui?
SALA Samui Chaweng Beach Resort in March

Hot and getting hotter. On average, March also has the fewest number of rainy days and, correspondingly, the least median cloud cover.


When's the Best Time to Visit Koh Samui?
Hansar Samui Resort on a REALLY hot day in April

REALLY HOT. April’s a scorcher. See where to stay, what to pack and what to expect on Koh Samui in April.


When's the Best Time to Visit Koh Samui?
Chaweng Beach in May

For that matter, May is pretty hot too (with more rainfall than March or April. When it’s this hot, the rain cuts the humidity and cools everything down – storms are gratefully received). As rainfall increases and humidity rises, you'll definitely want to up your mosquito warfare techniques. See where to stay, what to pack and what to expect on Koh Samui in May.


When's the Best Time to Visit Koh Samui?
Tango Luxe Beach Villas in June

June is a beautiful month on Koh Samui. If you schedule your trip before the school holidays begin, you'll usually find a very quiet island – certainly far fewer families than in July and August. See where to stay, what to pack and what to expect on Koh Samui in June.


When's the Best Time to Visit Koh Samui?
Koh Samui in late July

July and August are popular months on Koh Samui and for good reason. The differences in temperature and average number of rainy days between these two months are hair-splitting. Whether enjoying a northern hemisphere summer holiday or escaping southern hemisphere winter, it’s a great time of year to visit Koh Samui.


When's the Best Time to Visit Koh Samui?
My first visit to Koh Samui: Choeng Mon Beach in August 2003

I first visited Koh Samui in August, 2003 and … clearly, it was a pretty good sales pitch. August is fantastic but, as in July, afternoon showers are pretty common.


When's the Best Time to Visit Koh Samui?
Koh Samui in September

Just as nice as August but likely a lot quieter on the island. As of September 1st (when families head back for school), Koh Samui is all yours. As September draws on, expect it to get cloudier.


When's the Best Time to Visit Koh Samui?
Koh Samui in October

Starts out gorgeous (nicely hot and sunny). October on Koh Samui is, on average, one of the cloudiest months and it can be quite windy, too. Towards the end of October, rainy season might arrive.


When's the Best Time to Visit Koh Samui?
A stormy November day at The Tongsai Bay

Typically rainy season. Though it's as soggy as a sponge, I think November on Koh Samui has a lot to recommend it.


When's the Best Time to Visit Koh Samui?
A nice December day on Koh Samui

The tail-end of rainy season, not-quite-as-hot, but hopefully sunny. Just about perfect for a Santa hat and a Koh Samui Christmas.

What's Koh Samui weather like at Christmas?

With at least six or seven Koh Samui Christmases under my belt, I admit that your chances of sunshine aren't guaranteed. But your chances of finding homemade, freshly baked, Koh Samui mince pies? 100%.

When's the Best Time to Visit Koh Samui?
New Year's Eve on Chaweng Noi Beach

Should I go to Koh Samui in December?

If your alternative is being cold in a grey and miserable winter? Um, yes.

So when is the best time on Koh Samui?

Call me biased, but with fresh Samui coconuts on offer every day of the year… can there really be a bad time to come? Use The Koh Samui Guide to answer all your "what ifs", "how to's" and "where shoulds", then start planning the many ways you’ll enjoy the sun and rain of any season.

Koh Samui rain

How to rain-proof your Koh Samui holiday? When booking your accommodation (see where to stay on Koh Samui), look for outside areas that have covered overhangs (whether a balcony, patio or a restaurant or beach bar elsewhere within the resort).

1. Rain with an ocean view

Every room at Hansar Samui has an enormous ocean-view balcony (more like an outdoor living room). Unless the rain is coming in sideways, you’ll be able to enjoy any storms outside. Worst case? It’s exactly a 30-second walk to some of Koh Samui’s best bars and restaurants in Fisherman’s Village.

2. Rain with fresh croissants

Next door, Anantara Bophut also offers large, covered balconies and these are a great spot in a rainstorm. Easily turn yours into a rainy day picnic party: grab an Anantara golf umbrella, then order fresh croissants from room service. (Anantara’s bakery is amongst the best on the island). I’m telling you, rain is a good thing.

3. Rain with beer and a beach book

Beach-front restaurants, like those at Melati Beach Resort & Spa and Smile House, have see-through rain screens that roll down to keep you beach-front in any weather. Samui rainy days never mean cold weather, and you can often enjoy the dramatic atmosphere outside with your beer and a great book (while staying completely dry).

How do I come prepared for rain?

I don’t suggest packing wellies but, if rain is a concern, take a few tips from what to wear in rainy season. Three useful things to pack in case you're caught in an unexpected storm:

1. Waterproof mosquito-repelling wristbands

If your mosquito repellent washes off and you forget to reapply, these repellent bracelets are a great backup (and/or a lazy person's dream).

2. Waterproof phone case

This waterproof phone case also turns your phone into an underwater camera – Instagram, here you come! Also ideal for impromptu kayak trips and unexpected rain storms, described above.

3. Back-up power

Occasionally, strong storms can lead to temporary power outs so keep your Kindle charged and consider packing a back-up phone charger.

Does it rain often on Koh Samui? How long does it rain?

Koh Samui’s rainfall totally depends on the time of year. There’s rainy season, which can offer an astonishing volume of rainfall over a period of weeks. There’s a dry, extra-hot season. There are months when it rains a little every day – consistent but short-and-sweet rain showers. If nothing but sunshine is important, learn which are Koh Samui's sunniest months (above).

Does it rain all day in [month]?

To help choose when is best for you, see Koh Samui's month-by-month climate details, above. If you’re not aware of what you’ve signed up for, chances are you won’t find rainy season any kind of fun – as it can rain for days and weeks without ceasing. Otherwise, say in August, the world might end in wet fury for just 20 minutes.

What's the rain like on Koh Samui?

You know how Jurassic Park was super lush and green? And then it rained rather memorably? Same in Thailand: tropical country, requires regular watering. If you’ve never enjoyed hot, tropical rain – it’s pretty fantastic actually.

When the skies properly let loose, Koh Samui’s rain is easily described with a Forrest Gump quote. In rainy season especially, you might experience “every kind of rain there is. Little bitty stingin' rain... and big ol' fat rain.” If you’re coming from, say, Seattle or London where rain is a constant, often miserable, drizzle – Koh Samui rain might win you over.

Yes, it cuts into tanning time, but it's such a dramatic show you might not care. Take cover in a charming beach restaurant, a palm-thatched sala or an outdoor living room and enjoy the show. Tropical plants become greener than possible, and you can easily conjure some Robinson Crusoe elemental adventure.

Whatever the weather, The Koh Samui Guide is your trusty side-kick and will help make sure you have a fantastic vacation.

Have realistic expectations

How to actually enjoy a Koh Samui rainy day? (Yes, really!) Rather than having your holiday ruined by an afternoon or a few days of rain – try this little trick: Assume it will rain for at least part of your trip. That way, you’ll already have rainy-day activities that you’re looking forward to (and there are many – find a full chapter of ideas in The Koh Samui Guide).

How to avoid Koh Samui rain?

Koh Samui is a very hilly island (you’d generously call it mountainous) and has very localised microclimates. As such, visitors staying at one beach might experience a week of perfect sun, while those a few bays over see frequent thunderstorms. Outside of rainy season and days of determined ‘wet weather systems’, there’s every chance you could simply rent a car and drive elsewhere to find blue sky.

When's the Best Time to Visit Koh Samui?
A June day at SALA Samui Choeng Mon Beach Resort

When’s the Best Time to Visit Koh Samui?

So, when are you coming? Koh Samui will easily provide the beach holiday you’re dreaming of and, with a little preparation and a sense of adventure, you can enjoy its soggy sideshow in equal measure. Find more ‘glass half full’ honesty and insight in The Koh Samui Guide. In it, you'll get more activity ideas and logistical tips for every kind of weather (plus find out what not to do when it rains). Enjoy!

P.S. You can find every tip for Koh Samui weather in the archive, or subscribe by email and get all the details straight to your inbox. Enjoy!

Sources: World Weather Online, Weatherbase, Holiday-Weather.com and WeatherSpark.