The best time to visit Koh Chang is the November to April dry season, and December to February is the sweet spot: dependable sunshine, calm seas and the year’s lowest rainfall. The May to October monsoon is a different island, wetter than most Thai beach destinations at its peak, with rough seas, cancelled boat trips and a chunk of businesses shut, but also empty beaches, roaring waterfalls and heavily discounted rooms. This guide breaks down what each month actually looks like, what closes in low season, and when the value travellers should go. Climate figures below are long-term monthly averages, and any low-season discount figures reflect booking listings as of July 2026, so treat them as planning ranges rather than guarantees.
Koh Chang weather month by month
| Month | Avg rainfall | Typical highs | What it means for your trip |
|---|---|---|---|
| January | ~20mm | ~33°C | Peak season at its best; dry, sunny, calm seas; possible haze days |
| February | ~35mm | ~33°C | Still excellent; great snorkelling visibility; haze possible |
| March | ~70mm | ~33°C | Hot and mostly dry; first pre-monsoon storms; haze possible |
| April | ~125mm | ~34°C | Hottest month; Songkran 13-15 April; building humidity |
| May | ~395mm | ~33°C | Monsoon arrives; shoulder value; inter-island boats stop early May |
| June | ~515mm | ~32°C | Wettest month on average; very quiet; deep discounts |
| July | ~485mm | ~32°C | Wet core; short heavy bursts more than all-day rain |
| August | ~495mm | ~32°C | Wet core continues; rough seas, rip-current risk |
| September | ~500mm | ~32°C | Quietest month; waterfalls at full flow |
| October | ~300mm | ~32°C | Monsoon tapering; island reopens through the month |
| November | ~55mm | ~33°C | Shoulder sweet spot; drying fast, prices still soft early on |
| December | ~7mm | ~32°C | Driest month of the year; peak pricing from mid-month |
Rainfall and temperature figures are long-term monthly averages compiled by Climates to Travel; individual years vary, sometimes a lot.
When is the best time to visit Koh Chang?
November to April is the best time to visit Koh Chang, and December to February is the prime window within it. Average rainfall collapses from the monsoon’s roughly 500mm months to about 55mm in November, 7mm in December and 20mm in January, while daily highs sit around 32-33°C. The sea flattens out, which matters more here than on some islands: calm water is what makes the beach days on the west coast and the boat trips to the reefs off Koh Rang worthwhile, and dry-season visibility is when snorkelling around Koh Chang is at its best.
The trade-offs of peak season are the obvious ones. Mid-December to mid-January is the busiest and most expensive stretch of the year, and the popular stays on White Sand Beach and Klong Prao book out well ahead for Christmas and New Year. If those weeks are your only option, book early and expect peak rates; if you have flexibility, late January and February deliver near-identical weather with a little less pressure on rooms.
What is high season like from November to April?
Expect the Thailand of the postcards, with two caveats: heat and haze. From mid-November through February you are overwhelmingly likely to get sunshine, with only occasional showers, and this is the season to work through the full menu of things to do on Koh Chang, from the Kai Bae viewpoint to island-hopping day trips, without watching the sky.
The first caveat is that March and April turn genuinely hot. Highs commonly reach 34°C on average and can push to 36°C or more before the rains break, and the humidity climbs with them. It is still fine beach weather, but jungle hikes and waterfall walks belong in the early morning. Songkran, the nationwide water festival on 13-15 April, falls right in this stretch and is a fun, soaking counterpoint to the heat.
The second caveat is haze. From roughly January to March, smoke from agricultural burning in the wider region, including across the Cambodian border, can drift over the island and dull the skies, with air quality readings occasionally hitting unhealthy levels on the worst days, according to local reporting from island-based site I Am Koh Chang. It is a milder affair than northern Thailand’s smoke season, and plenty of days in the same window are clear, but photographers chasing saturated blue skies should aim for December and early January.
What happens on Koh Chang during the rainy season?
From roughly May to October the monsoon takes over, and June to September is the wet core, averaging around 485-515mm of rain a month per long-term climate data, which makes Koh Chang one of the wetter Thai islands at peak monsoon. The texture of that rain matters, though. Much of it falls as overnight downpours or short, violent bursts followed by sunshine, rather than unbroken grey days, and conditions can vary weirdly across short distances. As Ian, the long-term resident behind I Am Koh Chang, puts it: “it can be bright sunshine in Klong Prao and heavy rain in Kai Bae, just a couple of kilometers away.”
The practical impacts are the bigger story. Seas turn rough, and rip currents become a real hazard on the west-coast beaches, so there are days when swimming is off the table; read our Koh Chang beaches guide for which stretches are most exposed. Inter-island boats linking Koh Chang with Koh Mak and Koh Kood stop entirely from early May to mid-October, so island-hopping means backtracking via the mainland piers, where reduced speedboat services still run. A share of resorts, bars and tour shops close for the season, most noticeably on the quieter strips, while the main centres keep a working core open year-round. Storms occasionally knock out power when trees come down on lines, and the national park can temporarily close the Klong Plu and Than Mayom waterfalls after heavy rain if conditions are unsafe.
One thing that does not change: getting there. The car ferries from Ao Thammachat and Centrepoint piers near Trat run year-round across a short, sheltered strait, and weather cancellations are rare even at the height of the monsoon. Our getting to Koh Chang guide covers the full route from Bangkok.
Is the rainy season a bad time to visit?
Not necessarily, and for a certain kind of traveller it is quietly the best time. The island goes intensely green, the waterfalls run at full force instead of the dry-season trickle, the beaches empty out, and the resorts that stay open discount hard: cuts of up to about half off high-season rates show on booking platforms as of July 2026, though the exact discount varies by property, so confirm current prices when you book. September, and in many years June, are the quietest months of all, and if you are happy building days around a flexible weather rhythm, morning activity, afternoon downpour, evening clear, you can have long stretches of Koh Chang nearly to yourself.
Be honest with yourself about the failure mode, though. Multi-day wet spells do happen, boat trips get cancelled at short notice, the sea may be unswimmable for days at a time, and if your trip is a one-week beach holiday with no flexibility, a washout week in August will sting. Pick accommodation with some indoor comfort and a pool, and choose your base with the season in mind; our where to stay on Koh Chang guide flags which areas keep the most open in low season.
When is Koh Chang the best value?
May and November, the shoulder months, are the value sweet spots. Both often combine a decent amount of sunshine with pricing at or near low-season levels: May usually opens with dry-season weather lingering into the first weeks, and November dries out quickly after the monsoon while rates stay soft until the mid-December peak kicks in. You give up some certainty versus January, and in May the inter-island boats have already stopped, but the price-to-weather ratio in these two months is hard to beat. Early December before Christmas is a third, narrower window: essentially peak weather at pre-peak prices, if you can travel before the holiday rush.
Where to next
Lock in your season, then plan the rest: the getting to Koh Chang guide covers the Bangkok run and the ferries, the Koh Chang beaches guide helps you pick your stretch of sand, and the things to do on Koh Chang guide fills the days once you land. For what’s happening across the country while you’re planning, browse the live Thailand events listings.
Sources
- Climates to Travel: Ko Chang climate, monthly averages (long-term rainfall, temperature and sea data)
- I Am Koh Chang: Koh Chang weather and seasons (high/low season dates, heat, haze and air quality notes)
- I Am Koh Chang: The rainy season on Koh Chang (inter-island boat stoppage dates, ferry operation, waterfall closures, resident quote)
- Explore Koh Chang: Rainy season in the Koh Chang islands (seasonal closures, reduced mainland boat services, green-season conditions)
- Holidify: Best time to visit Koh Chang (low-season resort discounts)