Thailand in December: Weather, Crowds and What to Expect

December is Thailand at full throttle. The Andaman Coast is in prime dry season, the north is cool and clear, and even the Gulf islands have recovered from their October-November monsoon. The trade-off is price: Christmas week through New Year’s is the most expensive period of the year, and popular resorts fill months in advance. Early December (1st-20th) offers nearly identical weather at significantly lower cost.

Weather by Region

Bangkok is dry, warm, and comfortable at 26-32°C. December averages fewer than 10mm of rainfall — effectively zero rain. Humidity is low by Thai standards. This is one of the best months for walking the city’s temples, markets, and canal-side neighbourhoods without the heat exhaustion that arrives from March onward.

Chiang Mai and the north are in cool season — the best weather of the year. Overnight lows reach 12-16°C in the mountains (pack a light jacket), while daytime highs sit at 27-30°C. Skies are clear and the air is fresh. December is the last month before the burning season begins in February, so visibility for mountain viewpoints and trekking is excellent.

Andaman Coast (Phuket, Krabi, Koh Phi Phi, Koh Lanta) is in peak dry season. Rain is rare, seas are calm, and all islands are fully accessible. The Similan Islands are in their prime diving window. Ferries run full schedules to every Andaman island. Beach conditions are at their absolute best — clear water, no current warnings, and reliable sunshine.

Gulf Coast (Koh Samui, Koh Phangan, Koh Tao) has emerged from its November monsoon. Early December can still see occasional showers on Koh Samui, but by mid-December conditions are dry and sunny. Koh Tao diving visibility improves steadily through the month. The Full Moon Party on Koh Phangan — the December or New Year’s Eve edition — is one of the biggest of the year.

Diving and Snorkelling

December is excellent for diving on both coasts. The Similan Islands liveaboard season is in full swing — Richelieu Rock, Koh Bon, and Koh Tachai offer encounters with manta rays and whale sharks. Visibility reaches 25-30 metres. Book liveaboards 6-8 weeks ahead for December departures as Christmas-period trips fill quickly.

Koh Tao enters its improving winter season with visibility at 15-20 metres and calm seas. The combination of good conditions and high demand means dive boat group sizes are larger than in low season — book early-morning departures for smaller groups.

Festivals and Events

HM King Bhumibol Adulyadej Memorial Day (December 5) is a national public holiday and also celebrated as Thai Father’s Day. Yellow — the late King’s colour — is worn by Thai people across the country. Government buildings and main roads are decorated with yellow bunting and royal portraits. Some businesses close, but tourist attractions generally remain open.

Constitution Day (December 10) is another public holiday, though its impact on tourism is minimal.

The New Year’s Eve countdown at CentralWorld in Bangkok is Thailand’s largest New Year celebration, drawing hundreds of thousands. Koh Phangan’s Full Moon Party either falls on or near New Year’s Eve and becomes a massive multi-day event. Phuket’s Patong Beach holds a large countdown party with fireworks. All major beach destinations have New Year’s Eve events.

Prices and Crowds

December operates on two tiers. Early December (1st-20th) is high season with good weather and manageable prices — resorts charge high-season rates but availability is reasonable. Christmas week through New Year (December 22-January 2) is the most expensive period of the year. Phuket beachfront resorts charge peak rates with minimum-stay requirements. Koh Samui and Krabi are similarly inflated. Book accommodation 2-4 months ahead for the holiday period. Bangkok is busy but pricing remains more moderate than the islands.

Flights from Europe and Australia are at their most expensive in the final two weeks of December. Domestic flights within Thailand also increase, particularly Bangkok to Phuket and Bangkok to Chiang Mai.

Where to Go in Thailand in December

• Bangkok: Bangkok city guide
• Chiang Mai: Chiang Mai guide
• Phuket: Phuket guide
• Koh Samui: Koh Samui guide
• Koh Phangan: Koh Phangan guide
• Krabi: Krabi guide

Planning

See the best time to visit Thailand for a full seasonal comparison, or the Thailand budget guide for cost planning. Browse Thailand tours and day trips — book ahead in December as Similan Islands liveaboards and island day tours fill up fast over Christmas.