Koh Samui in December Weather, crowds and what to book

Is Koh Samui in December a good time to visit?

Yes, and it gets better as the month goes on. Koh Samui does not follow the rest of Thailand. Its wet season runs late, peaks in November, and is easing off by December. By the last week of the month the island is drying out into its dry season, just in time for Christmas and New Year.

That timing is the whole story of Koh Samui in December. The first half of the month is quieter and better value, with the tail end of the rains. The second half is sunnier and busier, and it builds to the biggest night of the year on Chaweng Beach.

We run ARKbar Beach Club on Chaweng Beach, Koh Samui, so we watch December happen from the sand every year. This guide is the weather in real numbers, the crowds as we see them, and what is worth booking before it goes.

What is the weather like in Koh Samui in December?

Warm, fairly sunny, and noticeably drier than November. The long-term averages from the WMO climate normals for Ko Samui, 1991 to 2020 put December at a daytime high of 29.3°C and a night-time low of 24.0°C. That is swimming weather all day and a light shirt at midnight.

The number that matters is rain, and it is falling fast. November is the wettest month on the island. December has around 40% less rain, and January less than half of December again.

What a rain day actually looks like

A rain day in the averages means any day with at least 1 mm of rain. On Chaweng that is usually a heavy shower that rolls in off the sea, empties for twenty minutes to an hour, and leaves the sand steaming. Whole days of grey are rarer, and they cluster in the first half of the month.

• Early December can still bring a run of wet days as the monsoon tails off.
• Mid December is mostly sun with the odd afternoon downpour.
• Late December is when the dry season shows up. It is why New Year works outdoors here.

Check the week you travel. Averages are averages. The Thai Meteorological Department publishes forecasts for the Gulf of Thailand coast, and they are worth a look five days out.

Can you swim in the sea in December?

Yes, most days. Chaweng faces east into the Gulf of Thailand, and in the tail of the monsoon the wind comes from the north east. Some mornings bring a real swell and churned-up water, and red flags do go up. By the afternoon it often settles.

When the sea is rough, the pools take over. Every beach club on the island leans on its pool in December for exactly this reason. Ours faces the sand, so you keep the view.

How busy is Koh Samui in December?

Quiet at the start, full at the end. December is really two months in one. From 1 to about 18 December the island is still quiet: the beaches have room, restaurants have tables, and hotels still have choice.

In our experience, from around 20 December everything changes. Families arrive for Christmas, then the New Year crowd lands on top of them. Chaweng Beach Road is at its busiest from Christmas Eve to New Year's Day, and the night of 31 December is the single busiest night of our year.

Is Koh Samui expensive in December?

The first half of the month is fair value. The last ten days are the most expensive of the year. In our experience, room rates across Chaweng climb from around 20 December, peak over New Year, and ease again in the first week of January. Flights follow the same curve.

The thing that costs most in December is leaving it late. Prices do not just go up, the choice disappears. In our experience, by mid November the best rooms on the beach for 30 and 31 December are gone.

What to book early, in order

• Flights into Samui. The island's airport is small and seats sell out over New Year. Bangkok Airways run most of the routes in.
• A room within walking distance of your New Year's Eve plan. Roads close and taxis vanish on the night. More in our guide to where to stay in Chaweng.
• Your New Year's Eve itself. Tables at ARKbar are on sale now, and the top tiers go first.
• Christmas Day lunch. Beachfront tables go weeks ahead.

What is on in Koh Samui in December?

December is the start of the island's big season, and the beach clubs programme accordingly. At ARKbar that means the daily pool party, which we cover in our pool party guide, international DJs through the Christmas week, and the fire show on the sand after dark.

• 24 and 25 December: Christmas Eve and Christmas Day parties across Chaweng.
• 26 to 30 December: the run-up week, with headline DJs most nights. See the Koh Samui nightlife guide.
• 31 December: the New Year's Eve Countdown Beach Festival at ARKbar, doors from 5:00 PM, fireworks over Chaweng Bay at midnight.

For the full plan for that night, read where to watch the New Year fireworks in Koh Samui.

What to pack for Koh Samui in December

• Light clothes, and one layer for a breezy night on the beach.
• A compact umbrella or a light rain jacket for the showers.
• Reef-safe sun cream. The sun is strong between the clouds.
• Something white or gold for New Year's Eve. Half the beach will be.

Stay inside the party

ARKbar Beach Resort

The resort sits inside the beach club on Chaweng Beach, so the countdown is downstairs and your room is a walk away. Resort guests get free general entry on 31 December 2026.

Premier Deluxe, 18 to 30 sqmDeluxe, 16 sqmBalcony in every room

See the rooms

For island-wide travel advice, the Tourism Authority of Thailand keeps an up to date guide to Koh Samui and the Gulf islands.

Koh Samui in December: your questions

So, should you come to Koh Samui in December?

Come early in the month for value and space. Come late for sun and the party. If you can only pick one week, pick the last one: the rain is easing, the island is at full volume, and it ends with fireworks over Chaweng Bay.

Whichever you choose, book the last ten days before November. That is the one piece of December advice we would give everyone.