Travel guide
Weather on Koh Samui & Koh Phangan
Samui and Phangan sit side by side in the Gulf of Thailand, so they share one climate — and it runs on a different clock from Phuket and Krabi on the Andaman coast. It’s warm all year (around 29–33°C); what changes is the rain.
Approximate long-term averages, last checked October 2026. Weather varies from year to year — this is a planning guide, not a forecast.
The three seasons
January – April
Dry season
Sunny, dry and calm — the classic beach season, with the best snorkelling and boat trips. February to April is the sweet spot; April is the hottest.
May – September
Hot, with short showers
Hot and mostly sunny, with brief tropical showers. While Phuket and Krabi get the monsoon, Samui and Phangan stay good — ideal for summer holidays.
October – December
Rainy season
The north-east monsoon brings heavy rain, peaking in November, with rougher seas. Quiet, green and the best value — it improves through December.
Month by month
Rainfall is what really changes through the year — temperatures barely move.
Green: dry · blue: some showers · amber: rainy · red: wettest. The table below has the same figures.
| Month | High / low | Rain | Sea | Beach days | What to expect |
|---|---|---|---|---|---|
| January | 29° / 24°C | Moderate ~140 mm | 27°C | ★★★★☆ | The rain eases off through the month; breezy, fresh and green. Some leftover swell on east-facing beaches early on. |
| February | 30° / 24°C | Low ~60 mm | 27°C | ★★★★★ | One of the best months: dry, sunny and not yet too hot. Busy — book early, especially around Chinese New Year. |
| March | 31° / 25°C | Low ~60 mm | 28°C | ★★★★★ | Dry, sunny and calm — clear water for snorkelling and boat trips to Ang Thong Marine Park. |
| April | 33° / 26°C | Low ~90 mm | 29°C | ★★★★★ | The hottest month, with glassy seas. Songkran (Thai New Year water festival) mid-month is huge fun. |
| May | 33° / 26°C | Moderate ~170 mm | 30°C | ★★★★☆ | Hot and humid with the odd tropical downpour, usually short and in the afternoon. Quieter and better value. |
| June | 32° / 26°C | Moderate ~130 mm | 29°C | ★★★★☆ | Mostly sunny with brief showers. While the Andaman coast (Phuket, Krabi) is in monsoon, the Gulf islands stay good. |
| July | 32° / 25°C | Moderate ~140 mm | 29°C | ★★★★☆ | A great summer-holiday month here — warm, mostly dry and much drier than Phuket. Popular with families. |
| August | 32° / 25°C | Moderate ~140 mm | 29°C | ★★★★☆ | Still good: sunshine with passing showers and a light breeze. Busy with European school holidays — book ahead. |
| September | 32° / 25°C | Moderate ~170 mm | 29°C | ★★★☆☆ | Showers become more frequent, but plenty of sunny spells and the lowest prices before high season. |
| October | 31° / 25°C | High ~290 mm | 28°C | ★★★☆☆ | The rainy season starts, usually in the second half of the month. Heavier downpours and quiet beaches. |
| November | 29° / 24°C | Very high ~480 mm | 28°C | ★★☆☆☆ | The wettest month: long rainy spells, rough seas on east coasts and occasional ferry delays. Great for long, quiet stays. |
| December | 29° / 24°C | High ~240 mm | 27°C | ★★★☆☆ | Rain tails off as the month goes on — late December is often lovely. Christmas and New Year sell out early. |
Samui & Phangan: which coast is calmer?
Same seasons, but the wind decides which beaches are calm — worth knowing when you choose a villa’s area.
Koh Samui
During the north-east monsoon (roughly November to January) the north and east coasts — Chaweng, Choeng Mon, Lamai — get the wind and waves, while the south and west — Lipa Noi, Taling Ngam, the south coast — stay calmer. From May to September it is the other way round, with a breeze on the west and calm water on the east.
Koh Phangan
Phangan shares Samui’s climate but its hills make the weather a little more local. In the rainy season, east-facing bays such as Thong Nai Pan and Haad Rin can be rough, while the west coast — Srithanu, Haad Yao, Haad Salad — is more sheltered. The monthly Full Moon Party at Haad Rin goes ahead in all seasons.
Samui & Phangan vs Phuket & Krabi
Thailand’s two coasts have opposite monsoons — when one is rainy, the other is usually fine.
| Months | Gulf: Samui & Phangan | Andaman: Phuket & Krabi |
|---|---|---|
| Jan – Apr | Dry & sunny | Dry & sunny |
| May – Sep | Mostly sunny, short showers | South-west monsoon, rough seas |
| Oct – Dec | Rainy season (peak Nov) | Drying out, good from Nov |
Good to know
Rain rarely lasts all day
Outside November, most rain falls in short, heavy bursts — often in the afternoon — followed by sunshine. A villa with a covered sala or terrace makes rainy hours easy.
The sun is strong all year
Even on cloudy days the UV is high. Bring reef-safe sunscreen, a hat and plenty of water — April and May are especially hot.
Allow time for boats in the rainy season
Ferries between Samui, Phangan and the mainland can be delayed or cancelled in storms, mostly in November and December. Leave a buffer before international flights.
Travel insurance
Weather is out of everyone’s hands — we recommend comprehensive travel insurance, as set out in our payment & cancellation policy.
Weather FAQ
What is the best time to visit Koh Samui and Koh Phangan?
February to April is the driest and sunniest, with the calmest seas. July and August are also very good — and much drier than Phuket or Krabi at that time of year.
When is the rainy season on Koh Samui?
Roughly October to December, peaking in November. Rain eases through December and January is usually pleasant again.
Is Koh Samui good in July and August?
Yes. The Gulf of Thailand misses most of the south-west monsoon that hits the Andaman coast, so July and August are mostly sunny with short showers — a popular family-holiday time.
Is the weather on Koh Phangan different from Koh Samui?
They share the same seasons — Phangan is only about 15 km away. Local conditions differ by coast: east-facing beaches are rougher in the north-east monsoon, west-facing ones more sheltered.
Can you swim in November?
Yes, the sea stays around 28°C all year, but waves can be big on east-facing beaches and red flags mean no swimming. Your private pool is the safe choice on stormy days.
Pick your dates, we’ll pick the villa
Tell us when you’re coming and we’ll suggest villas on the calmer side of the island for that time of year.