When Is the Best Time to Visit Koh Chang? A Month-by-Month Guide

Ask anyone who lives on Koh Chang which month is best and you will get a different answer each time. The fisherman says January, when the sea lies flat. The hiker says September, when every waterfall on the island is roaring. The barista at Sylvie Café says any morning the hornbills come in. They are all right, because Koh Chang is really three different islands in one year.

Here is the short version first, then the detail month by month.

The quick answer

• Best beach weather: November to February — dry days, calm sea, cool evenings. This is also the busiest and most expensive stretch, especially 20 December to 10 January.
• Clearest water for snorkelling and diving: February to April — hot, dry and glassy, with the best visibility around Koh Rang.
• Waterfalls, quiet beaches and the lowest rates: June to October, the green season. Expect real rain, mostly in bursts, and an island at its greenest.
• Best value with good weather: early November and March, the two shoulder windows.

Koh Chang's three seasons

Koh Chang sits in the Gulf of Thailand off the coast of Trat, close to the Cambodian border, and follows the same monsoon rhythm as the rest of Thailand's east coast. Trat is one of the rainiest provinces in the country, which is exactly why the island is covered in rainforest rather than scrub. The sea stays between 28 and 30°C all year, so the question is never whether the water is warm. It is whether the sky is clear and the sea is calm.

November to February: the cool season

The northeast monsoon pushes the rain away and brings the island its postcard weather: blue skies, a light breeze, daytime highs around 30°C and evenings that drop into the low twenties, cool enough for a walk on the beach after dinner. The west coast, where Kai Bae Beach is, faces away from the wind, so the sea in front of the resort is flat and clear.

This is high season for a reason. Christmas and New Year are the peak of the peak: our rooms and pool villas for those two weeks are usually booked months ahead, and rates are the highest of the year. Chinese New Year, in late January or February depending on the year, brings a second wave.

What to do: everything. Island-hopping and snorkelling boats run daily, the dive season is open, the hiking trails are dry, and the sunsets over the Gulf are at their most reliable.

Good to know: November is the transition month. The first half can still see a shower or two, and in return you get green hills, flowing waterfalls and lower rates than December.

March to May: the hot season and the clearest sea

From March the wind drops and the heat builds: 33 to 35°C by afternoon, with very little rain in March and April. The pay-off is the sea. With no wind and no run-off from the hills, the water around Koh Chang and the Koh Rang marine park is at its clearest, and this is the best time of year for snorkelling, diving and kayaking.

At low tide the sandbar to Koh Man Nai, the small island in front of Kai Bae, rises out of the water, and these calm, dry months are the easiest time to walk across. Songkran, the Thai New Year on 13–15 April, turns the island's villages into one long water fight and fills the resort with Thai families; book early if you want those dates.

May is the turning point. The heat breaks with the first afternoon storms, usually short and dramatic, with sunshine either side. Rates start to come down and the island empties out.

Hot-season tips: plan the beach and the boat for the morning, the pool and the Rainforest Spa for the afternoon, and drink more water than you think you need.

June to October: the green season

This is the season most guidebooks skip, and the one many of our regular guests choose on purpose. The southwest monsoon brings the rain. Koh Chang gets a lot of it: mostly heavy showers in the afternoon or overnight in June and July, and longer wet spells in August and September, the two wettest months. October tapers off, and by the end of the month the sea is usually calm again.

What you get in return: the rainforest at full volume, every waterfall on the island at its best, cooler air at 25 to 31°C, empty beaches, and the lowest rates of the year.

What to plan around: the west coast, including Kai Bae, takes the wind and the waves in this season, so there are days when the sea is for looking at rather than swimming in, and many snorkelling and dive boats pause or run fewer trips from around June to September. The ferry from the mainland runs all year, with fewer sailings than in high season. Bring a light rain jacket, repellent for the forest and a book for the afternoon storm. The pool, the spa, the café and the view are all still here.

If you want the green without the heaviest rain, aim for June, early July or October.

Month by month

Which month for your kind of trip

• Honeymoon or a big birthday: January to March, for guaranteed sunsets and a flat sea in front of the pool villa.
• Families with school-age children: December to April for the beach; July for the waterfalls if the children are happy in the rain.
• Snorkelling and diving: February to April. The dive season runs roughly November to May, and whale sharks are most often reported between December and May.
• Hikers and nature lovers: November for dry trails with full waterfalls; September if you want the forest at its loudest and do not mind getting wet.
• Wellness and slow travel: June to October, with the Rainforest Spa, the pool, the view and very few other people.
• Budget travellers: May to October for the lowest rates; early November and March for the best price-to-weather ratio.

Practical notes

• Getting here is the same in every season: fly or drive to Trat, then the car ferry from Ao Thammachat Pier, a crossing of about 30 minutes. Timetables, transfers and the map are on our How to get here page.
• Book early for 20 December to 10 January, Chinese New Year and Songkran. For the green season you can usually decide a week ahead.
• Pack reef-safe sunscreen in every month, a rain jacket from May to October, and a light layer for cool-season evenings.
• The hornbills that visit Sylvie Café do not keep a calendar. Mornings are your best chance in any month.

There is no wrong month to come to Koh Chang, only the wrong expectations. Decide what you want most, the flattest sea, the fullest waterfalls or the quietest beach, and the calendar above will point you to it. When you have picked your dates, see the rooms and villas at SYLVAN Koh Chang on Kai Bae Beach.