Thailand in December: Which Regions Fit a Two-Week Trip?

December is one of the two or three best months to be in Thailand, but not everywhere at once. The north is cool and clear, Bangkok is as dry as it gets, and the Andaman coast has just come out of its wet season. The Gulf coast has not: Ko Samui, Ko Phangan and Ko Tao are still in the wettest part of their year in November and the first half of December. So the region question is not "is December good" but "which coast, and how much of the month".

The short answer for a two-week trip: pair Bangkok and Chiang Mai with the Andaman side (Phuket, Krabi, Phi Phi, Ko Lanta), leave the Gulf islands for a trip from February onwards, and decide early whether your dates touch the Christmas and New Year fortnight, because that changes what you book first. The rest of this guide gives you the numbers behind that answer, region by region, and shows how the choice reshapes a 14-day route.

December at a glance, region by region

The figures are Thai Meteorological Department climate normals as published through the World Meteorological Organization. They describe an average December, not a forecast for yours, and a single storm can put a week of rain into a "dry" month. Use them to choose regions, not to plan a specific afternoon.

Two comparisons matter more than any single cell. Phuket goes from about 174 mm and 16 rain days in November to about 62 mm and 8 rain days in December, then to about 23 mm in January: the Andaman coast is drying out fast as December begins. Ko Samui goes the other way round the calendar, with November its wettest month and December still carrying more than three times Phuket's rain. That asymmetry is the whole reason a December trip should face west.

Bangkok and the central plains

December is Bangkok at its most comfortable: low humidity by local standards, warm rather than punishing afternoons, and almost no rain. Temple days that are a slog in April are pleasant now, and the river and canals are the right way to move. The city is busy in the second half of the month, with hotel prices rising towards New Year's Eve. Ayutthaya and Kanchanaburi day trips share the same dry weather if you have a spare day, though a two-week Bangkok, north and coast route rarely does.

Chiang Mai and the north

The north has the best month of its year. Dawn temperatures around 15 °C in Chiang Mai, cooler on Doi Suthep and Doi Inthanon, then warm, clear afternoons. Skies are at their cleanest now: the region's smoke season, when agricultural burning pushes PM2.5 well above standards, normally runs from January into April with the worst air from late February. A December visit sits comfortably before that window; an early-February visit is already a gamble.

If your dates can start in late November instead, Chiang Mai's Loy Krathong and Yi Peng lantern festival falls in the last week of November in 2026. The announced programme runs 24 to 26 November; confirm the exact dates before you build a trip around them, and expect the city's hotels to be full that week.

The Andaman coast

Phuket, Krabi, Phi Phi and Ko Lanta all enter their dry season as December begins, and by the middle of the month the sea is calm enough that island trips run daily and long-tail boats cross to Railay without drama. Maya Bay, closed every year from 1 August to 30 September, is open. Early December still sees the occasional afternoon shower on the coast, which is why the first week is quieter and cheaper than the last. If you are choosing between the two main bases, the Phuket or Krabi comparison works through flights, ferries and what each does to your nights.

The Gulf coast

Ko Samui, Ko Phangan and Ko Tao have their own calendar. The northeast monsoon brings the Gulf its heaviest rain from October into December: about 490 mm in November and about 209 mm in December on Samui, with rain on close to half the days. Ferries and flights still run, and some visitors get a dry week, but the odds are poor and the sea can be rough for diving and snorkelling. From February the Gulf comes into its own, and it stays good through the months when the Andaman side turns wet. For a December trip, treat the Gulf islands as a reason to come back in February or March, not as a base.

Beyond the three regions

If you are willing to trade a base, December also suits the places most two-week routes skip. Kanchanaburi, two to three hours west of Bangkok, is dry and green and pairs well with a slower first week. Sukhothai sits between Bangkok and Chiang Mai and can be added as a night on the way north by bus or by the daytime train and a short road transfer. Isaan, the northeast, has its coolest and driest weeks of the year now and almost no other foreign visitors. None of these fits a 14-day plan that already includes the north and the coast without removing something; they are reasons to spend December in Thailand for a third week, or to come back.

What December does not suit, beyond the Gulf islands, is anything that depends on high water: the northern rivers are low, waterfalls in the national parks are past their best, and rice paddies are being harvested rather than glowing green. If those are the photographs you want, the end of the rainy season in October and early November is the time, at the cost of wetter beaches.

Early December or the Christmas fortnight

The weather barely changes between 5 December and 28 December. Everything else does. The two weeks around Christmas and New Year are the coast's busiest and most expensive of the year: beach hotels fill first, then domestic flights around New Year's Eve, then boat tours. If your dates fall in that fortnight, book in this order: the coastal hotels, the domestic flights, the Bangkok and Chiang Mai hotels, then everything else. If your dates are flexible, the first ten days of December and the second half of January give you the same skies at a lower price and with fewer people on the boats.

Thailand's own holidays in this window are 5 December (the late King's birthday and National Day, with a substitute holiday on Monday 7 December in 2026), 10 December (Constitution Day), 31 December and 1 January. Christmas Day is not a public holiday. Tourism runs as normal on all of these; government offices close, and New Year's Eve fireworks in Bangkok and on the beaches draw big crowds.

How the region choice reshapes a two-week route

With the Gulf out and the Andaman in, a December fortnight has three sensible shapes.

• The classic three-region route. Bangkok 3 nights, Chiang Mai 4, Ao Nang 3, Phuket 3, flying between regions and taking the morning ferry between the two coastal bases. This is the 14-day itinerary with its day-by-day plan, buffers and booking order.
• North and coast, less city. Bangkok 2 nights on arrival, Chiang Mai 5 with a Doi Inthanon day and a free day, one Andaman base for 6 nights. Fewer transfers, more depth, and the best choice for families.
• Coast-heavy. Bangkok 2, Chiang Mai 3, then 8 nights split between Krabi and Phuket, or Phuket and Ko Lanta. Pick this if the beach is the point and the north is a detour you still want.

Whichever shape you choose, the Bangkok to Chiang Mai leg is a morning flight of about 1 h 20 or the overnight sleeper train that leaves Krung Thep Aphiwat at 18:40 and arrives at 07:15; the train or flight guide sets out what each does to your days. Chiang Mai to the coast is a non-stop flight of about two hours to Phuket or about 1 h 50 to Krabi, and the Ao Nang to Phuket ferry leaves at 10:30 in season.

What to pack for a December split

A light long-sleeved layer and long trousers for Chiang Mai mornings, the mountain temples and the sleeper train's air conditioning; the same clothes cover the dress code at the Grand Palace and every other temple. Reef-safe sunscreen, a hat and a dry bag for boat days on the Andaman. An umbrella is optional in December; a rain jacket is dead weight on this itinerary. Mosquito repellent matters more in the north's evenings than on the coast.

Entry rules for winter 2026–27

All foreign passengers must submit the free Thailand Digital Arrival Card online three days before arrival. Do it once the flights are booked and keep the confirmation with your boarding pass.

Photo credits

Wat Arun on the sunset by Trip.with.taste, CC BY-SA 4.0 (cover; resized for web display). Railay Beach Limestone Cliffs by Shivashanky, CC BY-SA 4.0. Both via Wikimedia Commons.