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Koh Samui, Thailand · Equatorial tropical

Koh Samui in January: go or not?

Mixed period. Koh Samui in January: 5.1/10.

📅 Updated August 2026 🛰️ ERA5 · 10 years 📍 9.51°N · 100.06°E
⚡ This month's verdict
Why not
Koh Samui · January
5.1
24–28°
Temperature
57%
Rain
6h
Sun
🌴 Tropical☀️ High UV🌧️ Monsoon season
Photo : RODOLFO BARRETTO via Unsplash
The month in detail

What to expect in January

January falls in the wet season in Koh Samui. Showers are often brief but intense. With 57.0% of rainy days, always have indoor alternatives planned.

January ranks 3 out of 12 months in Koh Samui. Compared to December: 6 pts fewer rainy days, +0.7h of sun per day.

This month's conditions

What it's like in January

UV index
8 · high
sunscreen and hat advised
Feels like
very humid
22°
Sea
28°C
warm, ideal
Daylight
11.5h of daylight
Air quality
fair
AQI 42
Compare

Is January the right month?

The best month in Koh Samui is March (5.5/10), 0.4 pt higher than January.

See March →See all 12 months →
Context

Our verdict

Koh Samui, Thailand's 2nd biggest island (88 sq miles) in the Gulf of Thailand: 60,000 inhabitants, more upmarket than Phuket, family beaches, base for Koh Phangan (Full Moon Party) and Koh Tao (diving). From January to August (6.6-6.9/10): 75-88°F, 35-67% rain.

Read Gilles' full review →

Book

Plan your trip

Hotels at their lowest outside peak season, highest on comfortable months. Shoulder seasons offer a good price/climate compromise.

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Stay
Hotels & rentals · Koh Samui
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Activities
Tours, tickets, experiences
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Flights
Multi-airline comparator
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🎟️ Activities & tours · Koh Samui

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Practical info

What you need to know before you go

Three angles: the country (language, currency, safety, budget), the year-round climate, and the specifics of a tropical stay.

Country · Thailand

🗣️LanguageThai
💶CurrencyThai Baht (฿)
🚗DrivingLeft-hand
🛡️Safety ⓘSafe · 2/5
💰Cost of living ⓘCheap · 2/5

🌡️ Climate

🌍Climate typeEquatorial tropical
📈Climate trend ⓘStable
🔥Hottest monthApril · 88°F
❄️Coolest monthJanuary · 82°F
🌧️Rainiest month ⓘOctober · 88%

🏝️ Tropical stay

🌞Dry season ⓘMay → Sep
🌧️Wet season ⓘDec → Mar
🌀Cyclones ⓘNone (equator)
Explore

Other destinations in January

If January doesn't convince you for this destination, compare with others.

Similar climate
Kota KinabaluMalaysiaHueVietnamNha TrangVietnamSaint ThomasUS Virgin IslandsMaldivesMaldives
Nearby
Koh TaoThailand70 kmKrabiThailand202 kmKoh Phi PhiThailand242 kmKoh LantaThailand247 km
Other top picks
BrisbaneAustralia5.3HarareZimbabwe4.6LilongweMalawi4.5JordanJordan4.4PetraJordan4.4
← DecemberFebruary →
🗺️ See all 754 destinations on the map
Location

Where is Koh Samui ?

Global position + regional geographic context.

🌍 World
🔍 Geographic context
Thailand
Equatorial tropical climate with a 5.5 → 4.5 gap between best and worst month. 10 years of ERA5 data to choose by project.
9.51°N · 100.06°E
Questions

Frequently asked questions

What is the best time to visit Koh Samui?
March is the best month with 86°F highs, 79°F lows, 7.7h of sunshine and 35.0% rainy days.
How many hours of sunshine does Koh Samui get in March?
Koh Samui averages 7.7 sunshine hours per day in March. It is the sunniest month with a climate score of 5.3/10.
What is the rainiest month in Koh Samui?
October is the most unfavourable month with October has the lowest climate score of the year and the lowest climate score of the year.
What are the temperatures at night in Koh Samui in March?
In March, overnight lows reach 79°F, while afternoon highs average 86°F.
Is Koh Samui good in winter?
In winter (December-February), Koh Samui scores 4.8/10 on average — Difficult period — prefer the peak season.. The best month overall remains March with a score of 5.3/10.
When should you avoid Koh Samui?
October is the most difficult month to visit Koh Samui, with October has the lowest climate score of the year. Climate conditions are at their lowest of the year during this period.
Can you swim in Koh Samui in January?
In January, the sea averages 82°F in Koh Samui: warm, ideal. Ideal conditions for swimming and snorkeling.
Do you need sun protection in Koh Samui in January?
The average UV index reaches 8 in January in Koh Samui (high), with about 11.5h of daylight. Sunscreen and hat advised.