As weather is one of the single most important factors when planning when and where to take your holidays, it’s important that you have all the weather facts to make an informed choice. Unfortunately, like everywhere in the world weather patterns have changed and become more unpredictable, but the following is a month by month guideline to what you can likely expect. The one thing you can be sure of, Koh Samui is always warm and the humidity remains high all year round ensuring you can leave your cold weather gear at home!

Balmy January

In January you can look forward to sunny, balmy days as it’s the coolest month of the year. The days are warm and the sea is refreshing and the Christmas revellers have returned home. The average daily temperature is a pleasant 26°C with clear skies and sunshine and little chance of rainfall. It’s peak  season on Koh Samui so expect it to be busy in the main resort areas and prices to reflect this, but the island is big enough and the sun is out so all is good in the world! If you are a keen diver or snorkeler, this is one of the best months to visit as seas are calm and the visibility is good.

Best thing to do

  • Head to Ang Thong Marine Park
  • Elephant ride

Glorious February

Like January, February falls in the dry season on Koh Samui, with an average of 8 hours of sunshine a day, it’s the perfect month for the sun seekers. The temperature keeps a “cool” 25°C to 28°C but be careful in the mid-day sun – it can be deceptive. Make the most of your holiday by getting out and about whether it be by the villa pool, exploring the island or taking a boat trip – get you vitamin D dose!

Best thing to do

  • Visit a waterfall which should be glorious after the monsoon rains.

Merry March

Things start heating up again in March as Koh Samui enters the hot season and with sun filled days, it’s one of the best months for the sun worshippers to visit the island. The average temperature is 29°C with high temperatures reaching around 31°C and warm 28°C sea temperatures. Historically, March 16 is the clearest day of the year so make the most of it as winter at home recedes to a distant memory! The Gulf of Thailand is calm, visibility is high and there’s an abundance of sea life and colourful reefs.

Best Thing to do

April heat

April continues to be dry and the heat rises throughout the month. There’s often a sea breeze when you are out and about and the a/c keeps you cool at the villa. The average daily high temperature in April is 32°C, lowering to around 26°C at night. Towards the end of the month there could be a chance of rain, but a few cooling showers may come as a welcome break from the heat of the day.

Best Thing to do

  • Diving – if you are lucky the whale sharks may be around.
  • Get involved in Songkran – the water festival.

Mellow May

May generally brings pleasant warm weather with a few rainy hours often accompanied by thunderstorms. Fear not, they  are generally over and done with fairly quickly. It’s still warm though, with an average daily high temperature of 32°C and cooling off to 26°C at night. It’s the beginning of the lower season so it does mean that if you are here at this time of the year, the tourist numbers will be less and you can enjoy some peaceful time on the island.

Best Thing to do

  • For those sailors take part in The Samui Regatta.
  • Take a picnic and enjoy a day on a deserted beach

 Sunny June

June is one of the hottest months of the year, with the average temperature in line with May – 33°C. Plenty of sunshine interspersed with a few rainy days – expect short, light showers. June 1st is the longest day of the year with a 5:59 am sunrise and the sun not setting till 6:37pm, so plenty of time to enjoy the beach and explore. As with May, the tourist numbers are lower so make the most of having a lot of beaches and attractions to yourself.

Best Thing to do:

  • For those golfer, attend the Queen’s Cup Golf Tournament at Santiburi Samui Country Club
  • For those runners – the Samui Marathon
  • Check out a walking street market in one of the villages

Hotting up in July

July continues to be hot but with the heat comes some cloudy days, which can be a bonus as the cloud offers some respite from the sun when you are busy exploring. The average July temperature is around 29 degrees Celsius and the sea is a bath-like 28°C! You could see some tropical weather with possible short thunderstorms and some light rain. This is also the month when the island starts filling up for the European summer holidays so expect to be sharing the island with lots of families.

Best thing to do

Family August

August is again one of the busiest months in Samui. Families from all over the world re-unite and meet in Thailand, escaping the crowded peak summer season in Europe. Great summer weather and long days make August one of the best months to visit with plenty of daylight hours and sunshine to explore and make the most of the island.  You can expect the odd rainy day but nothing that will affect your plans and beach time!

Best thing to do

  • Take a mountain safari Jeep tour through the jungle and hills of Samu


Cool, Calm September

September weather can be changeable, but It remains warm and there are often long days of sunshine. Be aware, that there could be cloudy days and the rain will start to fall more often as the month reaches its end. The average temperature is around 28 degrees centigrade and the water temperature begins to drop making the sea cooler.  After the August rush, the island quietens down again and you get the beaches to yourself.

Best thing to do

  • Try something new like zip lining or paddle boarding.

Relaxed October

Falling in the monsoon season, October can sometimes be a wet month in Koh Samui especially towards the end of the month. The average daily temperature is around 27°C, and drops to lows of around 24°C by the end of the month with cooler sea temperatures.  You can expect some days with light to moderate rain and the odd short thunderstorm. The humidity increases too, especially on sunny days. However, monsoon patterns have changed and you could be lucky with a glorious holiday of sunshine and lower temperatures. Towards the end of the month Ang Thong Marine Park may be closed due to high seas.

Best thing to do


Quiet November

And then there’s November! Warm weather, some sunny days but it is usually the rainiest month on Koh Samui – rough seas are expected.  The average daily temperature is around 29°C with lows to 26°C so still warmer than Europe! Days can be cloudy with some sunshine breaking through occasionally. The beginning of the month tends to receive the most rainfall. If you aren’t a sun seeker and are looking for a relaxed holiday to catch up reading and movies and totally spoil yourself with pampering days, then November could suit you as it’s quiet and prices are substantially lower. Be aware that some restaurants, bars and tour companies may close for a few days.

Best Thing to do

  • Pamper, pamper, pamper day!
  • Loi Khratong – the festival of light


Festive December

December marks the beginning of the dry season in Koh Samui ready for the Christmas break. As we move through December the skies start to clear and we see an increase in the number of hours of sunshine. And there’s more good news – the average temperature is 27°C, with lows 24°C and comfortable sea temperatures, making it sunny but relatively cool – the perfect combination. Businesses are readying themselves for the festive season and Ang Thong marine park re opens as life on Koh Samui wakes up after the monsoon and the fun and action restarts. The only down side is that prices rise dramatically as it’s the beginning of the 3 month long peak season.

Best thing to do

  • Christmas dinner on the beach and fireworks at New Year.
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