At a glance: region by region
| Region | December | January | Best for |
|---|---|---|---|
| Bangkok and central Thailand | Dry and cooler; about 7 mm of rain on the 30-year normal | Coolest month, dry, comfortable for city days | Temples, markets, food with kids |
| Northern Thailand (Chiang Mai) | Chilly mornings, cold on mountaintops; very little rain | Coolest month; pack a light layer for mornings | Elephants, nature, night markets |
| Andaman coast (Phuket, Krabi, Khao Lak) | Dry season begins; mostly sunny beach days | Peak dry season, calm seas | Beach holiday, island boats, snorkeling |
| Gulf coast (Koh Samui, Koh Phangan) | Rainy, especially the first half; storms possible | Drying out and improving through the month | Late-December and January beach days |
December: two different Thailands
The Thai Meteorological Department's seasonal outlook describes December as the month when high pressure from China covers the whole country and brings chilly, dry weather to the north, northeast and center, with cold temperatures in the mountains. The south is the exception: the northeast monsoon still brings abundant rain to the Gulf's east coast, mostly in the first half of December, and tropical storms can occasionally approach the lower south.
For a family that means: in the first two weeks of December, put your beach days on the Andaman side - Phuket, Krabi or Khao Lak - and keep Bangkok and the north for city and nature time. From the second half of December, Koh Samui starts improving, but if Samui is the heart of your trip, January is the safer bet. Our Koh Samui resorts with a kids club comparison and the resort we recommend for young kids help when you do go.
January: the reliable month
January is the coolest month across Thailand, with the lowest temperatures of the year, morning fog in central and eastern regions, and very little rain almost everywhere: on the 30-year normals, Bangkok's central region averages about 7 mm of rain on roughly one rainy day in the whole month. The south stays mild because of the surrounding seas, and the Gulf side finally dries. If your dates are flexible, January gives you the widest choice of coasts.
The trade-off is crowds and prices: the Christmas to New Year window and early January are the busiest, most expensive weeks of the Thai year. Book beachfront family rooms early, and check our Thailand family trip cost breakdown for realistic budgets.
Christmas break and New Year peak weeks
The Christmas and New Year school break (roughly 20 December to 4 January) is the busiest stretch of the Thai high season, with the highest hotel rates of the year around Christmas and New Year's Eve. If your dates are flexible, the first two weeks of December give you the same reliable Andaman-coast weather with thinner crowds. If your route starts in Bangkok over those dates, book the beach leg early.
Practical tips for these months
Pack a light layer. Chiang Mai mornings and air-conditioned malls can feel genuinely cool in December and January, especially for kids used to hot climates.
Keep sea days flexible on the Gulf side. In early December, boat trips around Samui can be cancelled for weather; book refundable activities where you can. Bookable options with free cancellation: Thailand tours and activities on Klook (12% off tours until 31 October 2026).
Split your trip. Our two-week Thailand itinerary with kids shows how to combine Bangkok days with an island week, and the family packing list covers the heat, rain covers and reef-safe sunscreen.
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Questions
Is December a good time to visit Thailand with kids?
Yes, with one regional caveat. Bangkok, central Thailand, the north and the Andaman coast are in their dry, cooler season in December. The Gulf side, including Koh Samui, still gets most of its rain in the first half of December before drying out toward January.
Is Koh Samui OK in December?
Early December is still the tail of Samui's rainy season, with most rain in the first half of the month and occasional storms. From the second half of December and into January, conditions improve markedly. If you travel in early December, prefer the Andaman coast.
December or January: which month is better?
January is the most reliable month nationwide: coolest and driest almost everywhere, including Koh Samui. December is excellent on the Andaman coast and in Bangkok but still rainy on the Gulf side in its first half. Prices and crowds peak around Christmas and New Year.
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Sources
Thai Meteorological Department: November-January climate outlook with 30-year normals (checked 20 October 2026)
Thai Meteorological Department: October-December 2026 seasonal outlook (checked 20 October 2026)
Thai Meteorological Department: December 2025 monthly weather summary (checked 20 October 2026)