When is the best time to go diving on Koh Tao? Unfortunately, there is no definitive answer, as the best time for you will depend on your overall wish list for your perfect Koh Tao dive holiday. Essential factors include excellent diving conditions, the chances of seeing particular marine life (most of our customers' bucket lists include whale shark diving), and of course, what the weather will be like on Koh Tao during your stay. After all, not all of your travel group may be here to go scuba diving. Koh Tao offers many other activities, but dry days are the best for most options.
We are lucky to have a very agreeable climate for most of the year on Koh Tao. Dive trips throughout the year see water temperature ranges from 26 to 32°C. There is no need for lots of neoprene for your wetsuit. Air temperature only varies by 10°C all year round, typically between 24 and 32°C – although it can certainly feel hotter in humid months! Most divers find a 3mm shorty wetsuit is fine, although many dive in board shorts and a rash vest. Another advantage of booking a Koh Tao dive holiday is that our wet season is short compared to most other Thailand diving destinations. Even compared to our nearest island neighbors, Koh Phangan and Koh Samui, Koh Tao sees much less rainfall.
To help you with your Thailand dive holiday planning, we have put together a yearly overview of Koh Tao diving conditions for you. Of course, there are never any guarantees when it comes to either weather or marine life sightings. But the good news for divers is an extensive range of dive site options, so it's generally always possible to select a safe spot for your Koh Tao PADI courses or fun dive trips. Koh Tao's hilly center means that if one side of the island is experiencing wing or choppy conditions, the other side will have calm and sheltered waters.
The end of the wet season can carry on into January, so diving conditions out at sea can be a little variable, and some wind may mean slightly choppy waters. Visibility is considered average, but around a new year has historically been a good time for whale shark sightings. Be prepared to share your experience if you are lucky enough to spot one. January is considered high season, so with more tourists on land, you can expect more divers underwater, too – especially at the most popular dive sites.
February is one of our favorite months for diving on Koh Tao. February brings good underwater visibility and calm surface conditions. It is not too humid on land, but towards the end of the month does get a bit fierier in the lead-up to the hot season. It is still a busy month with divers enjoying the excellent conditions below and above water.
Another month where whale shark sightings are possible on Koh Tao dive trips, March marks the beginning of peak heat season. So remember your sunscreen, shades, and hat, as you don't need to be on the top deck long before you burn. It is generally quieter, meaning less traffic on dive sites and optimal visibility.
The perfect month for those who like it hot! April is usually the driest and hottest month all year on Koh Tao. If you want to party, April is an excellent month to visit as Songkran (Thai New Year) is celebrated on April 13th. Sunny on land, with exceptional visibility underwater, and still with a fair chance of a whale shark sighting, this is a popular time for fun divers who have booked Koh Tao dive packages with us.
May in Koh Tao is still hot and sunny but starting to cool a little compared to April. There is still a lingering chance of whale shark sightings, and the ocean is typically calm with good visibility underwater. It is one of the quietest times around Koh Tao dive school and dive sites, making it a favored month for regular Koh Tao scuba lovers.
June is the low season on Koh Tao, so if you want quieter dive sites and less crowded bars, restaurants, and beaches, this is a great month to visit. The humidity and high temperatures of peak heat season have dissipated. Still, with the monsoon season beginning on the West coast of Thailand (Phuket, Krabi, Koh Phi Phi, Koh Lanta), it is possible to experience some rainfall.
The start of July remains quiet on Koh Tao, but from mid to end, our second peak season begins as European families and backpackers take their summer holidays. Isolated rain showers are still possible, and on the surface, it is generally cooler than the previous months, yet conditions at sea and underwater remain generally good.
The Koh Tao island is still busy with European summer holidaymakers, and underwater visibility remains above average. August can be unpredictable, and while some years are gloriously sunny and calm, others can be windy, which brings a choppier element to Koh Tao's dive trips. You can expect sporadic rainfall, but storms are typically quick to blow over.
Another of our favorite months in Koh Tao! Cooler conditions on land, sunny weather, and calm, flat seas. Plus, the island gets quieter again after the first week once the European school and university holidays end and families and students return home. Historically, September is another excellent month for whale shark sightings, so fingers crossed!
Back when the seasons were a bit more predictable, you could rely on October to be satisfactory for most of the month, with similar conditions to September – including the possibility of a whale shark dive. In the past, the last week of October has been windy as monsoon storms make their way toward Koh Tao, bringing with them waves and reduced visibility. Bear in mind, however, that the wet season has pushed back in recent years and does not typically arrive until November/December in Koh Tao.
November has provided fine weather and dive conditions for a few consecutive years in Koh Tao, and the monsoon arrived in December. November is the wet season equivalent to May. Low season means quiet streets on land and fewer divers underwater. However, as November is typically when monsoon season has begun, we can't guarantee good diving conditions. Based on recent years, however, if you take a chance on November diving in Koh Tao, you could beat the odds.
December in Koh Tao can be unpredictable, depending on what the monsoon has decided to do. But in general, you can expect choppier seas, rain, and reduced visibility. That being said, reduced visibility underwater can sometimes help diving to see more varied marine life as reef inhabitants explore further from their hiding places, knowing they cannot be seen so easily by any predators. Plus, diving in December is always fun as around Christmas time, you'll see many divers in Santa hats, and the upcoming new year has always been a likely time for whale shark sightings.