Thailand (Koh Samui)
Thailand · Asia
The best time to visit Thailand (Koh Samui) is February, March, April, and August. In summer, daytime highs average 34°C (93°F), with peaks around 35°C (95°F); in winter, nights average 26°C (79°F), dropping to around 22°C (72°F) on the coldest. During the best travel months, the sun shines up to 9 hours per day — ideal for beach and outdoor activities.
Thailand (Koh Samui) – What you should know
Koh Samui lies on the east coast of the Malay Peninsula and follows the east coast rain rhythm of Thailand — the opposite of Phuket. The best travel time is December to April: dry, sunny weather with temperatures of 27–32°C (81–90°F) and calm seas for snorkelling and boat tours to Koh Pha-ngan and Koh Tao.
From October to December — especially November — the north-east monsoon hits Koh Samui with the heaviest rainfall of the year. Flooding and rough seas are not uncommon then. Those who want to visit Thailand at this time are better off switching to the west coast (Phuket, Krabi), which has its best weather then. From May to September, the weather is variable but often still swimable, with short afternoon showers.
Climate Overview
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Ø day, range from coolest to warmest dayØ dayrange | 31° (88°)27– (81–)32 (90) | 31° (88°)29– (84–)32 (90) | 32° (90°)29– (84–)34 (93) | 33° (91°)29– (84–)35 (95) | 34° (93°)31– (88–)35 (95) | 33° (91°)30– (86–)35 (95) | 33° (91°)30– (86–)34 (93) | 33° (91°)30– (86–)34 (93) | 33° (91°)29– (84–)34 (93) | 32° (90°)28– (82–)34 (93) | 31° (88°)27– (81–)33 (91) | 31° (88°)27– (81–)33 (91) |
Ø night, range from coldest to warmest nightØ nightrange | 26° (79°)22– (72–)27 (81) | 26° (79°)23– (73–)27 (81) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)29 (84) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)27 (81) | 26° (79°)24– (75–)27 (81) | 26° (79°)24– (75–)27 (81) | 26° (79°)23– (73–)27 (81) |
☀️Sunshine | 8h UV 8 | 9h UV 9 | 10h UV 9 | 9h UV 9 | 8h UV 9 | 8h UV 8 | 7h UV 8 | 8h UV 8 | 6h UV 8 | 6h UV 7 | 6h UV 7 | 7h UV 7 |
🌊Water Temp | 28° (82°) | 29° (84°) | 30° (86°) | 31° (88°) | 31° (88°) | 30° (86°) | 30° (86°) | 30° (86°) | 30° (86°) | 30° (86°) | 29° (84°) | 28° (82°) |
🌧Rain Days | 8d154mm (6.1") | 4d66mm (2.6") | 4d112mm (4.4") | 6d101mm (4.0") | 11d152mm (6.0") | 10d120mm (4.7") | 11d142mm (5.6") | 8d95mm (3.8") | 11d122mm (4.8") | 15d239mm (9.4") | 16d474mm (18.7") | 11d310mm (12.2") |
Best travel timeØ = average · small figures = range: coolest–warmest day / coldest–warmest nightClimate data 2005–2025 · Source: ERA5 + station data
Travel Tips
From February to August, UV levels in Thailand (Koh Samui) reach 9 — very high on the WHO scale. High-SPF sunscreen and shade around midday are essential.
January offers great weather in Thailand (Koh Samui) with fewer tourists and lower prices — ideal for those who want to avoid the peak season crowds.
Events & Festivals
April
- Songkran (Thai New Year)· 13–15 April
Southeast Asia's biggest water festival turns Chaweng and Lamai into one huge water party. People drench each other with water pistols and buckets — traditionally a blessing for the new year.
May
- Samui Regatta· varies (late May, 8 days)
Asia's most prestigious sailing regatta off Chaweng Beach. Yachts from around the world compete over several race days, with sundowner parties on the beaches in the evenings. The event is part of the international sailing calendar.
Frequently Asked Questions
- When is the best time to visit Thailand (Koh Samui)?
- The best time to visit Thailand (Koh Samui) is February, March, April, and August. These months offer the most favourable combination of sunshine, temperatures, and low rainfall.
- How warm does it get in Thailand (Koh Samui)?
- In summer, daytime highs in Thailand (Koh Samui) average 34°C (93°F), with peaks around 35°C (95°F); in winter, nights average 26°C (79°F), dropping to around 22°C (72°F) on the coldest.
- How much rain does Thailand (Koh Samui) get?
- Thailand (Koh Samui) has a relatively even rainfall pattern with an average of 10 rain days per month. The driest months are February, April, and August.
- How warm is the water in Thailand (Koh Samui)?
- Water temperature in Thailand (Koh Samui) ranges from 28°C (82°F) (January) to 31°C (88°F) (May). During the best travel months (February, March, April, and August), the water is most pleasant for swimming.
Best Travel Time by Vacation Type
🏖️
Beach Holiday
Warm, sunny, little rain
JanFebMar
🏙️
City Trip
Pleasantly mild, not too hot
JanFebDec
