Koh Samui in April: Weather, Songkran and Travel Tips
Koh Samui in April is the hottest month of the year — and still one of the most popular times to visit. Short answer: yes, April is worth it if you can handle the heat and plan around Songkran, when things get busier and pricier. The sea stays calm, Ang Thong National Park is open all month, and rain days are still manageable.
At a glance
| Metric | Value |
|---|---|
| Air temperature avg | 32°C by day / 26°C at night |
| Rainfall | around 80mm over roughly 6 rain days |
| Sea temperature | around 30°C |
| Sunshine hours/day | approx. 7 |
| Sunrise/sunset (mid-month) | approx. 6:10am / 6:30pm |
| Season | tail end of high season, busiest around Songkran (13–15 April) |
| Crowds / prices | high, peaking around Songkran, noticeably quieter right after |
We couldn't find a reliably sourced figure for daily sunshine hours on Koh Samui, so we've deliberately left it out rather than guess.
Weather in April
April is statistically the hottest month on Koh Samui, with daytime highs around 32°C and little relief at night. The roughly 6 rain days are mostly short, intense afternoon or evening downpours — often thunderstorms that build up over the island and clear within an hour or two. Mornings are almost always dry and sunny.
Wind and waves are generally mild on both coasts in April, since neither the southwest monsoon (which mainly affects the Andaman coast around Phuket and Krabi) nor the northeast monsoon (which brings Koh Samui's real rainy season from October) is active. That makes April one of the more reliable months for boat trips and inter-island ferries.
What to do in April — and what not to
Ang Thong National Park is open as normal in April (the 2026 closure runs only from 1 November to 15 December), and the crossing is usually calm — one of the best months for the boat trip out to the limestone islands:
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Snorkelling trips to the southern islands also run reliably in April, with generally good underwater visibility thanks to the calm sea:
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Beaches on both coasts are equally usable in April, since there's no pronounced rough side of the island yet, unlike later in the rainy season. If you do get caught in one of the short afternoon showers, a shopping mall, an air-conditioned temple tour, or one of the indoor ideas would work well for filling the gap.
Festivals and events in April
Songkran, Thailand's New Year and water festival, is by far the biggest event of the month. It officially runs from 13 to 15 April every year — confirmed for 2027 via a Bank of Thailand announcement in the Royal Gazette. On Koh Samui, celebrations often start a day early and run one or two days longer, with Chaweng and Lamai in particular guaranteed to leave you soaked. For more on how the festival works, see our Top 10 Events in Thailand.
If you'd rather skip the water fights, plan your trip just before or after Songkran — the weather barely differs from the rest of the month.
Fruit in season
April kicks off two of Thailand's favourite fruits: durian and mangosteen both start their main season, running through to September. Lychee (season roughly April to June) also starts appearing at markets, while mango is at some of its best quality of the year (main season February to July, peaking March to June). More on all the fruit and their seasons in our Top 10 Fruits in Thailand.
What to pack for April
Because of the heat, light, breathable clothing, strong sun protection and a reusable water bottle are the essentials. For the short afternoon showers, a small rain jacket or an umbrella from a convenience store is usually enough — you won't need a bulky raincoat this early in the year. If you're planning to join the water fights in Chaweng or Lamai during Songkran, a waterproof phone pouch is worth adding to the list.
Frequently asked questions
Is April a good time to visit Koh Samui?
Yes, with one caveat — heat. April is statistically the hottest month, but the sea is calm and Ang Thong National Park stays open throughout. If you want to avoid crowds, plan around the Songkran dates of 13–15 April.
How hot is Koh Samui in April?
Daytime temperatures average around 32°C, with nights barely cooling below about 26°C. The sea is a pleasant 30°C or so.
Does it rain in Koh Samui in April?
Only on around 6 days on average, usually short, heavy afternoon or evening showers. Koh Samui's real rainy season doesn't start until October.
When is Songkran on Koh Samui?
Officially 13 to 15 April every year (the 2027 dates are confirmed), though celebrations on Koh Samui often start earlier and run a little longer.
For the month before, see Koh Samui in March, and for what comes next, see Koh Samui in May. The full climate table with the monsoon explanation is in Koh Samui weather and the truth about the rainy season, and a year-round overview is in Best time to visit Koh Samui.
Keep reading
Koh Samui in August: Weather, Sea and What's On
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Koh Samui in December: Weather, Holidays and What to Do
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