Thailand has a tropical, warm, and humid climate year-round, with differences between the north and the south. The average air temperature in South Thailand is around 28°C (82°F). It is important to note that Thailand has two main seasons, dry and rainy. In reality, it has two dry and two rainy seasons, which differ based on the location. Luckily, you can find rain-free areas all year round to go diving in Thailand, either in the Gulf of Thailand or the Andaman Sea.
Diving in Thailand at a glance
How good diving in Thailand is?
General recommendations about the best time to visit Thailand
The air temperature is usually between 24°C and 30°C (75°F and 86°F) during the day, while it can drop to 21°C (70°F) at night. While Thailand’s climate is tropical, it is essential to note that the country is vast, so temperatures decrease in the north.
If you want to avoid the crowds, crazy traffic, and higher accommodation prices, try not to travel to Thailand during the holidays of December, January, Easter, Christmas, Chinese New Year, and Golden Week. Accommodation prices will be much lower, and road traffic will be more manageable outside these periods.
What you need to know about the rainy season:
A key piece of information to know: In Thailand, the rainy season isn’t all over the country at the same time. There are two rainy seasons. While the part of Thailand from Chiang Mai to Phuket via Bangkok (Northern, Central and Andaman Coast) has its rainy season from May to October, the Gulf of Thailand (Koh Samui and Koh Tao) has its rainy season from October to January. So, if you do the math, the best season to go scuba diving in Thailand, on both the West and East coasts, is from February to April.
Regarding the best diving conditions, water is at its clearest in the Andaman coast from February to April and in Koh Tao from March to June. If you consider that the peak season to see whale sharks is February-March, especially in Koh Tao, where there have been more sightings in recent years, that leaves us with a sweet spot in March/April. However, you can dive all year long in Thailand by choosing the area wisely. Regarding water temperatures, you can always expect warm waters, usually between 26 and 30°C. I recommend a 3mm full wetsuit (in case you run into a jellyfish bloom).
In any case, due to the conditions at sea, the Similan and Surin Marine National Parks are closed from the 16th of May to the 14th of October every year, and the dive sites of the Lanta Marine National Park are closed from the 1st of July to the 30th of August. These annual closures allow the ecosystems to recover from the tourism pressure at a time when it’s not ideal to visit anyway. Well done, Thailand!
Average diving conditions in Thailand
While Thailand´s water temperatures can be expected to be pretty constant between 28°C and 30°C (82°F – 86°F), note that the temperature can drop with depth and currents. Also, if you travel to Thailand during the rainy season (May to October), the water temperature could be nice and warm, but the wind and rain on the boat could make the way back from the dive site feel quite chilly.
In Thailand, visibility varies with the amount of rainfall; it can drop to 10 m (*) during the rainy season and reach 40 m (*****) in the heart of the dry season. In January, a visibility drop in the Andaman Sea isn´t unusual if plankton arrives with the current.
Diving in Thailand in January
January marks the peak tourist season in the Andaman Sea, occurring in the middle of the dry season there. Still, the visibility can drop significantly due to plankton in the current. In the Gulf of Thailand, January is the shoulder season and the last month of the rainy season.
Conditions Phuket & the Andaman Sea:
- Average water temperature at the surface: 28°C (82°F)
- Air temperature: min 26°C – 29°C (79°F-84°F)
- Average days of rain: 4
- Visibility: ** (1-5 star)
Conditions Koh Tao & the Gulf of Thailand:
- Average water temperature at the surface: 27°C (81°F)
- Air temperature: min 29°C – max 29°C (79°F-84°F)
- Average days of rain: 3
- Visibility ***** (1-5 star)
Peak season:
Chinese New Year, the public Chinese holiday, marks a peak tourist season; the exact dates change every year between January and February.
Diving in Thailand in February
February is one of the months when you can dive on both sides in the South of Thailand, as they are both in the dry season. The Andaman Sea is still in the high season, while the Gulf of Thailand is in the shoulder season, with the first month of dry season already underway there.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 26°C – 29°C (79°F-84°F)
- Average days of rain: 3
- Visibility: ***** (1-5 stars)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 28°C (82°F)
- Air temperature: min 26°C – max 29°C (79°F-84°F)
- Average days of rain: 3
- Visibility ***** (1-5 star)
Peak season:
Chinese New Year, the public Chinese holiday, marks a peak tourist season; the exact dates change every year between January and February.
Diving in Thailand in March
Most of March is the shoulder season, during which the weather is a bit better on the Gulf of Thailand side, although both areas are still in the dry season.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 27°C – max 30°C (81°F-86°F)
- Average days of rain: 11
- Visibility: ***** (1-5 stars)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 28°C (82°F)
- Air temperature: min 27°C – max 30°C (81°F-86°F)
- Average days of rain: 4
- Visibility ***** (1-5 star)
Peak season:
Easter is a peak tourist season due to the European and Australian holiday period, with the exact dates changing every year between March and April.
Diving in Thailand in April
April is the last month when you can go diving on both sides of southern Thailand. The dry season ends in the Andaman Sea, and the Gulf of Thailand reaches its high season.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 30°C (86°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 10
- Visibility: *** (1-5 star)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 7
- Visibility ***** (1-5 star)
Peak season:
Easter is a peak tourist season due to the holidays of people from Europe and Australia; the exact dates change every year between March and April.
The last week of April is a peak tourist season due to Golden Week holidays in Japan.
Diving in Thailand in May
May marks the beginning of the rainy season in the Andaman Sea and the peak season on the Gulf of Thailand side, where the peak dry season occurs.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 30°C (86°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 15
- Visibility: ** (1-5 star)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 10
- Visibility ***** (1-5 star)
Peak season:
The first week of May is a peak tourist season due to Golden Week holidays in Japan.
Marine parks closures:
Similan and Surin Marine Parks are closed from 16th May till 14th October.
Diving in Thailand in June
June is the beginning of the rainy season in the Andaman Sea. The Gulf of Thailand reaches its peak season in the middle of the dry season on this side.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 30°C (86°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 16
- Visibility: ** (1-5 star)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 14
- Visibility **** (1-5 stars)
Peak season:
The first week of May is a peak tourist season due to Golden Week holidays in Japan.
Marine parks closures:
Similan and Surin Marine Parks are closed from 16th May till 14th October.
Diving in Thailand in July
July is high season in the Gulf of Thailand because it is the middle of their dry season, whereas it’s low season in the middle of the rainy season on the Andaman Coast.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 16
- Visibility: ** (1-5 star)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 16
- Visibility ** (1-5 star)
Peak season:
July is a peak tourist season because of the summer holidays for people in Europe.
Marine parks closures:
Similan and Surin Marine Parks are closed from 16th May till 14th October.
Lanta and Phi Phi Marine Parks are closed from 1st July till 30th August.
Diving in Thailand in August
August marks the end of the high and dry season in the Gulf of Thailand and the low season, while it is the middle of the rainy season on the Andaman Coast.
Conditions Phuket:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 15
- Visibility: ** (1-5 star)
Conditions Koh Tao:
- Average water temperature at the surface: 28°C (82°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 16
- Visibility ** (1-5 star)
Peak season:
August is a peak tourist season due to the summer holiday in Europe.
Marine parks closures:
Similan and Surin Marine Parks are closed from 16th May till 14th October.
Lanta and Phi Phi Marine Parks are closed from 1st July till 30th August.
Diving in Thailand in September
September is the shoulder season, with the last month of the dry season in the Gulf of Thailand. The Andaman Sea reaches its peak of the rainy season and is considered low season.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 17
- Visibility: * (1-5 star)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 28°C (82°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 19
- Visibility * (1-5 star)
Marine Parks Andaman Sea:
Similan and Surin Marine Parks are closed from 16th May till 14th October.
Diving in Thailand in October
Most of October is shoulder season on both sides. It is the last month of the rainy season in the Andaman Sea and the first month of the rainy season in the Gulf of Thailand.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 18
- Visibility: * (1-5 star)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 28°C (82°F)
- Air temperature: min 28°C – max 31°C (82°F-88°F)
- Average days of rain: 18
- Visibility * (1-5 star)
Marine Parks Andaman Sea:
Similan and Surin Marine Parks are closed from 16th May till 14th October.
Diving in Thailand in November
Most of November is shoulder season in the Andaman Sea, marking the first month of the dry season. The Gulf of Thailand reaches its low season in the middle of the rainy season.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 29°C (84°F)
- Air temperature: min 27°C – max 30°C (81°F-86°F)
- Average days of rain: 12
- Visibility: *** (1-5 star)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 28°C (82°F)
- Air temperature: min 27°C – max 30°C (81°F-86°F)
- Average days of rain: 17
- Visibility *** (1-5 stars)
Diving in Thailand in December
December is the peak season and dry season in the Andaman Sea and the low season in the middle of the rainy season in the Gulf of Thailand.
Conditions Phuket & Andaman Sea:
- Average water temperature at the surface: 28°C (82°F)
- Air temperature: min 26°C – max 29°C (79°F-84°F)
- Average days of rain: 9
- Visibility: ***** (1-5 stars)
Conditions Koh Tao & Gulf of Thailand:
- Average water temperature at the surface: 27°C (81°F)
- Air temperature: min 26°C – max 29°C (79°F-84°F)
- Average days of rain: 12
- Visibility *** (1-5 stars)
Peak season:
The end of December with Christmas and New Year’s Eve is a peak tourist season due to the European and Australian public holidays.
Do you need more information to plan your trip to Thailand?
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