Koh Tao is situated in a sub-tropical climate in Southern Thailand. The island is affected both by NE- and SW- Monsoons. The NE- Monsoon dominates from the end of October to the beginning of December, where you can expect the weather to be heavy rainfall. The SW- Monsoon (June to Sept.) is mild since Koh Tao is sheltered both by the mainland and the surrounding islets.
Koh Tao is unique since it offers a 10 month high season for travelers to visit and enjoy the beauty of the Island. Peak seasons are from February to April, and again from July to September. During these months the weather on Koh Tao is generally hot (up to 40 degrees C) with very little rain.
Below is described a rough description of the weather you can expect during the different months of the year. Although as we know weather patterns are disturbed around the world, so at best this is only a guide line. Sometimes the best weather comes in the middle of the monsoon, while at others times we have seen the peak season full of rain. You can contact us to get an update on Koh Tao weather at occasion.
Divers: you can also Check out the current viz on Koh Tao or and see the most recent water temperature graph below.
Perfect months of full sunshine and comfortable air temperature (average for sea and air temp.28-30 degrees) During these months we have high tides allowing easy access to prime snorkeling sites straight off the beach. The water on the west coast of the island is completely flat calm but visibility can be a little temperamental with the knock on effects of monsoon seas especially in early Jan. As the sea calms down during this period the visibility improves making February one of the best months to visit Koh Tao , especially when most of the western world is in the middle of the depressing winter months.
March, April & May Weather… Dry season
In these months the temperature warms up, great for sun lovers. The water is flat and calm, & everyday is guaranteed sunshine and gorgeous sunsets! As the days are dry and humid sometimes leading to some good tropical style thunderstorms especially at dusk but they’re usually on the mainland, watch the amazing light show over the sea while you sip on your après dive beer sitting on the beach. Water clarity is best during this time & your chances of seeing Whale sharks are much higher than at any other time of year.
June, July & August Weather… Indian summer
The wind turns at this point of year, blowing all the way across the Indian Ocean so by the time the wind hits the west coast of thailand the waves are big and powerful. fortunately koh tao is on the east coast of Thailand so the wind slows down as it passes over the mainland. However we do get a fresh cooling breeze & occasional days of relatively big waves. If the monsoon is heavy on the west coast, it can rain at this time, afternoon storms can be very typical especially in August but they don’t last long & weather is still generally pretty sunny throughout the day. Diving is best on the East side of the island where the sea is flat and calm, crystal clear & teeming with marine life. A good season for turtles too.
September & October Weather… Tropical autumn
Very beautiful warm sunny days, calm flat seas and superb diving conditions. Water & Air temperature drops a little as we enter the ‘winter’ months but it’s still tropical. This is my favorite time every year on the island, good visibility, low humidity and of course sunsets to die for. Average daytime air & water temperature is around 28 degrees. Fish life is abundant around these weeks and the famous whale shark often comes to give us a visit, especially during October, when there are not so many divers.
November & December Weather… Monsoon Season
Koh Tao doesn’t suffer from relentless rain for days on end. A typical monsoon usually consists of a couple of weeks on & off of impressively hard rain & quite a lot of wind. The visibility gets stirred up & the swell can be rather unpleasant. This is Koh Tao weather at its worst and its really not that bad! When the weather clears up the island looks fresh and green. The journey to Koh Tao at this time of the year is mostly going to be bouncy, now a days there are good boat companies that can get you safely to the island even in big swells. The island is very quiet at this time and you can experience the Koh Tao of old, with few people on the beaches and uncrowded dive boats, of course we like that.
The New Heaven Reef Conservation Program is closed during this time, from Nov. 15th – Dec. 15th. The Dive School remains open all year.