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What is the Weather Like on Koh Tao?

“What will the weather be like during our stay on Koh Tao”?…. Its a common question, and of course an understandable one – who doesn’t want perfect conditions for their holidays?!?!

The good news for our divers is that we have a huge range of dive sites on the island (50+), and thanks to the orientation of Koh Tao and how quick it is to circumnavigate, it’s normally easy for us to select dive sites that are suitable for any course or trip you’d like to take with us – whatever the weather! We are very lucky to have such an amenable climate on Koh Tao, and although we have a wet season, it is very short compared to many other tropical destinations. Plus we get less rain in general than our neighbours on Koh Phangan and Koh Samui, thanks to the small size of the island itself, and a lack of any mountains high enough to break those pesky low lying rain clouds. Full details on what conditions you can expect throughout the year as follows….

Great visibility at Koh Tao dive site Mango Bay
Sun Rays Underwater


January can be a mixture of conditions with the tail end of the monsoon season still around the sea conditions can be a bit up and down, the visibility is improving but the surface conditions maybe slightly choppy. The water temperature is about 27C, which is the lowest it will get around Koh Tao; the air temperature is similar to the water temperature, so it’s warm but not humid. January marks the start of high season on Koh Tao, so there will be a lot of people about; of all ages, you have backpackers starting their trips and families enjoying the New Year in the sunshine.


In February the conditions are good the visibility is between 10-15m on average, the surface is mostly calm and the water temperature is usually between 27-29C. The air temperature is warm and comfortable for most of the month, towards the end of the month it starts getting a little hotter. February is one of the busier months on the island with a lots of visitors arriving on our shores to take advantage of the great conditions – both above and below the surface!

Sunny Koh Tao
Sunny Koh Tao


This month is the start of the hot and dry season for the east coast of Thailand, there is very little rain if any this month. The diving conditions are great, perfect for divers and snorkelers as well as being the perfect temperature for the corals reefs to grow. There is typically a chance of spotting Whalesharks from March onwards for a couple of months too. So bring your go pro’s and underwater housings – you might just get that perfect profile photo!


April is the driest and hottest month of the year on Koh Tao but that doesn’t stop the fun. April is also the month Thai New Year (Songkran) falls in on the 13th and 14th April, which is celebrated with an island wide water fight. Locals and holiday makers alike all joining in the fun, and it is definitely a day to remember! April is also the official start of ‘Whaleshark season’ on the East coast of Thailand; the visibility is great this month, ranging between 15-20m. Surface conditions are generally calm in April and the temperature of the water is around 30C.

Whale Shark!
Whale Shark!


May is the beginning of the quieter months on Koh Tao, it is also the start of the cooler season as well, this month will see temperature start to fall and there may be a chance of rain showers. This is a great time to come and relax as the island is quieter in general. There is also still a chance of spotting a Whaleshark in May as this month and the diving conditions are good with calm seas, clear visibility, and water temperatures averaging 30C.


June is a great month for people who want to get away during quiet season as the island is in a peaceful lull before the European summer holidays start in mid-late July. The weather is cooler this month as well. The diving conditions are slightly mixed as the island can sometimes see some rain as a result of the monsoon season on the west coast of Thailand. This can alter surface conditions and visibility, but for most of the month both are great, the water temperature is about 29C this month – perfect conditions for both divers and marine life alike!

Beach life



With the start of the European Summer holidays the island starts seeing a lot more families and backpackers this month. The weather is still cooler than the hotter months of April and May as well as staying continuously sunny with some rainfall from the monsoon that is hitting the West Coast of Thailand. The rain however, if it does come, usually only stays for an hour or two. Visibility is usually between 15-20m on a good day and the surface is generally calm.

August can sometimes be a mixed bag both weather and condition wise. There is a bit more rainfall this month but is usually doesn’t rain for long. The water conditions can change between being choppy and flat calm depending on how hard the wind is blowing. Water temperature is still stable at around 29C this month and visibility is between 10-15m.

Mango Bay
Mango Bay


September is still peak season with lots going on, and generally fine weather and good dive conditions in terms of visibility and calm seas. Any rain is typically quick to blow over and has little impact on underwater conditions. Normally the ambient temperature starts to drop a little, in the lead up to the cooler months of October and November. Expect water temperatures of around 28-29C.

October can still be busy on the island but towards the end of the month the island generally quietens down as the weather and diving conditions start to become poorer. The weather can change quite quickly in October with winds bringing in rain for a couple of hours in the afternoon to then drying up quickly. The water conditions are choppier on the surface and the visibility can range from 10-15m depending on recent weather. The temperature is around 28C.

Koh Tao is full of postcard worthy beauty
Grey Skies over Koh NangYuan


November is the peak of low season here on Koh Tao, this is when the monsoon weather typically hits the island. You can expect rains and high winds, however in recent years, the monsoon isn’t as powerful as it used to be due to climate change. The air temperature is around 27C. The water conditions are probably at its lowest this month, the temperature is the same as the air; 27C, surface conditions can be very wavy and this visibility can be between 3-10m. If you are after a challenge and are keen on becoming a more experienced diver these are great conditions to dive in!

December can be a bit unpredictable depending on if and when monsoon has decided to arrive! The poorer conditions can continue through from November, which can limit the dive sites we go to. Water temperature is around 27C, visibility can range from 5-15m, and surface conditions can still be choppy. The up side is that in the past few years there has been a number of whale shark sightings around Christmas/new year time.

We hope this helps with your weather questions and planning. If you have any further questions, feel free to contact us for more information 🙂

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