The best time to visit Koh Samui
Koh Samui is one of Thailand's most popular islands, but one of the most misunderstood when it comes to weather. Get the timing right and it's spectacular. Get it wrong and you're watching the rain from a sun lounger.
Here's what you need to know.
The best time to visit Koh Samui overall
December to March is the most reliable window for weather - less rain, hot but not suffocating and calm, clear seas. If you can get away at this time of year and you don’t mind paying peak season prices, this can be a great time to visit. Book ahead though - the best properties go fast.
Koh Samui’s weather pattern
Koh Samui doesn't follow the same weather pattern as the rest of Thailand. While Phuket and the Andaman Coast get drenched between May and September, Samui largely escapes that monsoon making it a decent option for a summer holiday (and worth knowing if you've ever ruled out Thailand in July).
Season by Season
December to February - dry season
Peak Koh Samui. Temperatures between 25°C and 30°C, minimal rain and long sunny days. Christmas and New Year are busy and festive. Book well ahead.
March to May - hot season
March has the fewest rainy days of any month. April brings Songkran (Thailand's water festival) which is worth experiencing if you're there. By May it's properly hot. Brilliant if you love the heat.
June to August - the quiet peak
Often overlooked. May and June offer good weather with noticeably fewer crowds and the sea is at its clearest, ideal for snorkelling and diving. July and August pick up with European families on school holidays, but it's still a long way from the chaos of January.
October to November - avoid if you can
The northeast monsoon arrives in October, bringing the heaviest rainfall of the year and choppy seas. Spa lovers and those after a quiet retreat can still have a good trip at a lower price. But for a beach holiday, this isn't the time.
December — transition month
Early December can be unpredictable. From mid-month it starts to settle. It can work well, but it's the one time of year worth keeping a close eye on the forecast before you travel.
Our Recommendation
For a classic luxury escape, February or March is hard to beat. For families, July works well. For couples after something quieter and better value, May or early June is a strong choice, with good weather, clear water and far fewer people.
Wherever you go in Koh Samui, the resort matters enormously. The island has some of the finest properties in Asia and some that don't come close to the brochure.
FAQs
Is Koh Samui good in the summer? Yes, and it's one of Thailand's best-kept secrets for summer travel. While Phuket gets hit by the monsoon, Koh Samui largely avoids it. June and July offer good weather, clear water and a fraction of the January crowds.
How hot does it get? Expect 25°C to 33°C year-round. March and April are the hottest months. Even in the cooler dry season, it's warm enough to swim and sunbathe every day.
Is it worth visiting during the rainy season? Depends what you're after. October and November bring heavy, unpredictable rain and rough seas, which are not ideal for a beach holiday. If you're happy spending time in spas, restaurants and exploring the island, you can still have a good trip. Just go in with realistic expectations.
How far in advance should I book? For December to February, as early as possible. Three to six months ahead is sensible for the best properties. For shoulder season travel in May to August, two to three months is usually sufficient, though popular villas and smaller boutique resorts fill up quickly.
Can I combine Koh Samui with other destinations? Easily. Bangkok is a natural add-on, either at the start or end of your trip. Koh Tao and Koh Phangan are short boat rides away for day trips or island-hopping. Or combine with a jungle stay with glamping in Chiang Mai or Elephant Hills.
