Thailand’s weather is typically warm and humid but when deciding the best time to visit, it’s worth noting that there are with distinct tropical wet and dry seasons. There are two separate monsoon seasons: the south-west monsoon season between June and October affects the northern, central and south-western parts of the country, while between October and December, it’s the south-eastern coast and Gulf of Thailand that receive most of their rain.
Overall, temperatures average around 24⁰C-32⁰C with pleasant nights, although if you’re visiting Chiang Mai and Chiang Rai in Northern Thailand, it’s best to pack a light jumper to prepare for the chilly nights during the south-west monsoon season. Peak season between November and February is one of the best times to visit, as most of Thailand stays dry and sunny and average temperatures are around 27⁰C-31⁰C.
Low season in Thailand (around May-October) can be very wet everywhere except for Koh Samui and Koh Phangan, however rainfall varies between torrential downpour and short bursts, and travellers who don’t mind braving the rain or staying in resort can benefit from great value offers and quieter attractions. If you’re visiting in low season, it’s worth packing a light waterproof and checking the daily forecast for an accurate indication of incoming showers; rainfall can range from grey skies and downpours every day to warm, sunny days with short showers that clear up quickly. For diving and snorkelling, the Surin and Similan Islands marine parks are open mid-October to mid-May when weather is more favourable.
Here’s our month-by-month guide to Thailand’s weather and climate.
In January, Thailand’s weather is fairly warm and dry with lower levels of humidity and 9 hours of sunshine. Northern Thailand is cooler, particularly at night, so an extra layer is recommended for those visiting Chiang Mai and Chiang Rai. If you’re headed for the beach, Phuket and Khao Lak on the west coast are ideal with plenty of sunshine. There may still be some rain in the east around Koh Samui.
February is a great month to visit Thailand. Weather is warm and mostly dry both in the north and south and lower humidity makes it pleasant for sightseeing and outdoor activities. Good visibility and warm water temperatures of 27⁰C makes it ideal for snorkelling and diving around Koh Phi Phi and the Surin and Similan Islands.
Thailand’s climate begins to get warmer in March with average highs of 35⁰C and very little rain, making it ideal for beach holidays. Snorkelling and diving is still very good with sea temperatures of 29⁰C. Crop burning in Northern Thailand reaches its peak levels in March and April, meaning air in Chiang Mai can become quite polluted – something potentially worth looking into for those with health concerns.
Thailand is at its hottest in April with high humidity and temperatures rising up to 40⁰C. There can be short showers which offer welcome relief from the heat. Rain is more likely on the west coast in Phuket and Khao Lak while the east coast offers better weather for those wanting to snorkel, dive or sunbathe. The Thai New Year, Songkran, is a three-day national celebration in April, most notably marked by the huge street water fights – a welcome refreshment from the scorching heat.
As Thailand’s south-west monsoon season begins, temperatures remain warm at around 30⁰C but it is more humid with heavy rain pour – around 180mm. The Gulf of Thailand in the east is the exception which is yet to experience their separate monsoon which begins later in the year. Here, beach goers can enjoy hot and generally much drier weather in Hua Hin and Koh Samui. The Similan Islands National Park closes annually in May as the seas become rougher.
June is likely to see downpours across north, central and south-eastern Thailand, although these tend to be short and most of the days will remain pleasantly warm and humid with average temperatures of around 29⁰C. The east coast including Koh Samui and Koh Phangan see less rain and offers better diving options.
Thailand is wet and warm in July, with heavier rainfall particularly in the north, west coast and central Thailand. The east coast will often only experience occasional afternoon showers.
August is another rainy month in Thailand, with plenty of rainfall and humidity expected in Chiang Mai, Bangkok and Phuket on the west coast. On the east coast, Koh Samui will be sunnier and drier than the rest of the country but will start to see more rain and cloudy days.
Thailand in September is increasingly wet with rainfall across most of the country. In the Gulf of Thailand off the eastern coast, the rainy season is just beginning when the weather becomes cloudier and wetter. We’d recommend considering Bali as an alternative for sunshine and drier weather in Southeast Asia, and fewer crowds too.
October is the last month of the main rainy season, when days are unpredictable with heavy showers and spells of pleasantly warm weather. Cooler temperatures of around 25⁰C makes it one of the more comfortable rainy season months to travel around, and there are good value deals on offer that some travellers might consider is worth the changeable weather.
Thailand enters its high season in November with pleasant, drier weather with the rain tapering off the further into the month you go. The Andaman coast in the south-west has 7 hours of sunshine and average temperatures of 27⁰C, making it a more favourable beach destination than the Gulf of Thailand which will start to see experience more rainfall.
December is one of the best months to visit Thailand, with little rainfall and lower humidity levels. Average temperatures are around 26⁰C on the Andaman coast and 27⁰C in Bangkok. In northern Thailand, a light jumper is advised for when temperatures can fall from 28⁰C in the day to 15⁰C in the evenings.