Best time to visit Thailand: weather by region

Thailand is warm all year – in Bangkok the average daytime high is above 30 °C in every single month. So the question of the best time to go is really a question about rain, and rain does not fall everywhere at the same time. The north and Bangkok have a classic summer rainy season, as does the west coast on the Andaman Sea, while the islands in the Gulf of Thailand get theirs in late autumn. We analysed the weather data for 2015 to 2024 for four places and tell you when to go where.

The short answer

• Best time for the whole country: December to February. Bangkok and the north are dry, nights in Chiang Mai are cool, and it is the dry season on the Andaman coast around Phuket and Krabi.
• Hot season: March to May. Bangkok averages 34.3 °C in April, Chiang Mai 35.6 °C. In the north, smoke from field burning often hangs in the air.
• Rainy season: May to October in Bangkok, the north and on the Andaman coast. Rain usually comes in short, heavy showers rather than all day.
• The exception, the Gulf of Thailand: On Koh Samui, Koh Phangan and Koh Tao most rain falls from October to December. From February to August it is comparatively dry – the best beach region for a trip in the northern summer.

Bangkok's climate: all 12 months

Temperatures and rain: monthly averages 2015–2024 from the ERA5 reanalysis (Open-Meteo), rounded. Values apply to a grid cell of about 25 km; the city centre is often a little warmer still.

What stands out is how little the temperature changes: the coolest and hottest months in Bangkok are only just over three degrees apart by day. The difference lies in the nights and the rain. In December and January it cools to around 22 °C at night, and only 19 to 24 mm of rain fall. In September, the wettest month, it is 292 mm – more than ten times as much.

Three regions, three rainy seasons

Rain: monthly averages 2015–2024, ERA5 reanalysis (Open-Meteo), rounded.

The table shows the pattern clearly. On the Andaman Sea in the west, the southwest monsoon brings a lot of rain from May to November; the driest month is February with 29 mm. In the rainy season the waves are often high too: swimming is dangerous on some beaches, and boat trips are cancelled in bad weather. In the Gulf of Thailand it is the other way round: from June to August Koh Samui gets only 77 to 99 mm, and the peak comes in November with 288 mm. In the north around Chiang Mai the contrast is greatest: 10 mm in March, 387 mm in August.

Base map: Natural Earth

Thailand month by month

November

The transition: Bangkok gets only 71 mm, Chiang Mai 48 mm, and it becomes more pleasant. On the Andaman coast an average of 239 mm still falls, though it usually gets drier towards the end of the month. In the Gulf, November is the wettest month of the year. Usually in November, depending on the lunar calendar, Thailand celebrates Loy Krathong, the festival of lights; in Chiang Mai lanterns rise into the sky at the same time for Yi Peng.

December to February

The best time for Bangkok, the north and the west coast. In Chiang Mai the average January night drops to 16.2 °C, with a comfortable 27 °C by day – ideal for temples, markets and trips into the mountains. On Phuket, February is the driest month with 29 mm; Krabi gets 46 mm. It is peak season: around Christmas and New Year flights^* and accommodation are at their most expensive and book up early. The Gulf only dries out from February; in December and January Koh Samui still gets 223 and 132 mm.

March and April

The hottest time of the year. Bangkok reaches 34.3 °C by day and 26.7 °C at night in April, Chiang Mai 35.6 °C. In the north, farmers burn fields during these weeks and smoke often settles in the valleys – if you are sensitive to it, avoid Chiang Mai in March and April. The beaches, on the other hand, are good: Koh Samui gets only 38 mm in March, the Andaman coast 52 mm. In mid-April Thailand celebrates Songkran, the traditional new year, with water fights in the streets. It is an experience – but expect to get wet, and remember that many Thais travel themselves during these days.

May to October

The rainy season in Bangkok, the north and on the Andaman coast. Rain mostly comes in heavy showers in the afternoon or evening, and the sun often comes out again afterwards. The country is green, the rice fields are flooded, and it is much quieter and cheaper than in winter. For the beach, the Gulf is now the better choice: from June to August Koh Samui gets only 77 to 99 mm. On the Andaman coast, boat trips to the islands depend more on the weather at this time. From September it rains a lot everywhere, and in October in the Gulf as well.

Which beach at which time of year?

The rule of thumb is simple: in the northern winter, head to the Andaman Sea – Phuket, Krabi with Ao Nang and Railay, Koh Lanta or the Phi Phi Islands. In the northern summer, head to the Gulf – Koh Samui, Koh Phangan or Koh Tao, which is popular with divers. In March and April both coasts are good; in October and November neither is really dry, and late November on the Andaman coast is then the better bet.

Island trips, snorkelling tours and ferries are best booked once you know the forecast for your days. You can find tours on the Andaman coast^* at Klook, for example, and ferries between the islands and buses to the mainland on 12Go^*.

Bangkok and the north

Bangkok is best visited at the start or end of your trip, for two or three days: the Grand Palace, Wat Pho with the reclining Buddha, Wat Arun on the river and the street food of Chinatown. In the heat, schedule sightseeing for the morning and late afternoon; at midday, air-conditioned museums and malls help. For the temples you need clothes that cover your shoulders and knees.

Bangkok trip planDay by day, with map and tips

The north around Chiang Mai and Chiang Rai is at its best in December and January, when the nights are cool and the air is clear. From Bangkok you fly to Chiang Mai in about an hour, or take the overnight sleeper train. How to combine Bangkok, the north and the beach in two weeks is explained in our Thailand itinerary for 2 weeks.

How YesTrip helps with this trip

In YesTrip you'll find a ready-made city plan for Bangkok with temples, the river and markets, which you can adopt and fit to your travel days. For Chiang Mai and your beach, the AI creates a day plan with a map. The weather forecast covers your travel days – so you can see whether to move the boat trip to the next morning. The packing list remembers light, covering clothes for the temples, a rain jacket in the rainy season and the right plug adapter. Travelling with others, you share the trip and log shared expenses; the map also works offline on the islands.

What to know before you go

• Entry: UK and EU citizens do not need to apply for a visa in advance for short tourist stays; your passport must be valid for at least six months. The rules have changed several times recently – check the current requirements on gov.uk or with your own government.
• Flight: from London, direct flights to Bangkok take about 11.5 hours. Domestic flights continue to the islands, and Koh Samui can also be reached by ferry from the mainland.
• Power: 220 volts. Sockets are mixed; European plugs often fit but not everywhere – pack an adapter.
• Temples: cover shoulders and knees, and take off your shoes before entering the buildings.
• Mobile data: a travel eSIM is much cheaper than roaming and helps with maps and taxi apps.

If you travel in April you will catch the New Year festival; where to celebrate it is in Songkran 2027.

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