Thailand Koh Samui Weather in December — Climate Guide
December in Koh Samui is moderate
Koh Samui Weather in December — Quick Answer
As of 2026- Avg temp
- 28° / 24°
- Rainfall
- 230mm · 17 days
- Crowds
- Very busy
As of 2026, Koh Samui in December averages a high of 28°C and low of 24°C with 230mm of rain over about 17 days. Wet season easing late month, but still rainy early on — and cooler than usual. Around 28°C/24°C. Light clothing plus a rain jacket and umbrella; quick-dry fabrics help. Sea ~29°C.
December is moderate for Koh Samui.
December is a month of two halves on Koh Samui. Early December still sees significant northeast-monsoon rain (the month averages around 230mm), but the rains ease through the month and conditions improve markedly toward late December. It averages 28°C/24°C — the coolest of the year, which is mild and pleasant.
Early-month travelers can still hit wet, choppy weather with affected boat trips, while those arriving for Christmas and New Year often catch the start of the dry-season turnaround, with calmer seas and more sun returning.
Travel score
Koh Samui December Weather Stats
Avg High
28°C
Avg Low
24°C
Rainy Days
17
230mm total
Sunshine
5h
Daily avg
Humidity
84%
muggy
UV Index
9
Very high
Wind
15 km/h
Gusts 30
Sea Temp
29°C
Avg water temp
Crowds
Very busy
At attractions
December Sunrise & Sunset
Air Quality
PM2.5
13 μg/m³
PM10
24 μg/m³
Status
good
Feels-Like Temperature & Wind
Feels like
Daytime
33°C
Nighttime
26°C
Humidity and wind affect how the actual temperature feels.
Wind
15 km/h
Max gust 30 km/h
Activities Recommended for December
December Travel Pros & Cons
Pros
- Weather improving through the month
- Coolest, mildest temperatures of the year
- Calmer seas and more sun by late December
- Festive Christmas/New Year atmosphere
Cons
- Early-month monsoon rain still likely
- Yearly-peak Christmas/New Year prices
- Book 4-6 months ahead for the holidays
- Boat trips unreliable early month
December Events & Festivals
- Wet season easing through the month — drier by late December
- Christmas & New Year peak travel — yearly-high prices
- Boat trips improving late month
- Slightly cooler temperatures
Koh Samui in December — Full Picture
December is a month of two halves on Koh Samui. Early December still sees significant northeast-monsoon rain (the month averages around 230mm), but the rains ease through the month and conditions improve markedly toward late December. It averages 28°C/24°C — the coolest of the year, which is mild and pleasant.
Early-month travelers can still hit wet, choppy weather with affected boat trips, while those arriving for Christmas and New Year often catch the start of the dry-season turnaround, with calmer seas and more sun returning.
Despite the lingering rain risk, Christmas and New Year are the year's biggest travel peak, with the highest hotel prices and busy beaches — book 4-6 months ahead for the holidays.
The Gulf timing keeps shifting: Samui is emerging from its wet peak just as the Andaman coast is in full dry-season swing, so early December still favors the west coast, while late December evens out.
The sea is warm (~29°C). For the most reliable December weather on Samui, aim for the second half of the month.
What to Wear & What to Pack
Wet season easing late month, but still rainy early on — and cooler than usual. Around 28°C/24°C. Light clothing plus a rain jacket and umbrella; quick-dry fabrics help. Sea ~29°C.
Packing Checklist
Seasonal Weather Overview
Spring (Mar·Apr·May)
31.7°C
25°C
10/mo
Summer (Jun·Jul·Aug)
32°C
25°C
13.3/mo
Autumn (Sep·Oct·Nov)
30°C
24.3°C
18/mo
Winter (Dec·Jan·Feb)
Current29°C
24°C
12.3/mo
Koh Samui Monthly Weather Comparison
| Month | High | Low | Rain | Sun | Humid | UV | Crowd | Price |
|---|---|---|---|---|---|---|---|---|
| 29° | 24° | 14d·180mm | 6.5h | 82% | 10 | Very busy | Peak | |
| February (Best) | 30° | 24° | 6d·60mm | 8h | 78% | 11 | Very busy | Peak |
| March (Best) | 31° | 25° | 7d·75mm | 8.5h | 78% | 12 | Busy | Peak |
| 32° | 25° | 9d·100mm | 8.5h | 78% | 12 | Busy | Peak | |
| 32° | 25° | 14d·150mm | 7h | 80% | 11 | Moderate | Shoulder | |
| 32° | 25° | 13d·110mm | 7.5h | 78% | 11 | Busy | Shoulder | |
| 32° | 25° | 13d·110mm | 7.5h | 78% | 11 | Very busy | Peak | |
| 32° | 25° | 14d·110mm | 7h | 78% | 11 | Very busy | Peak | |
| 31° | 25° | 15d·150mm | 6h | 80% | 10 | Moderate | Shoulder | |
| 30° | 24° | 19d·290mm | 5h | 84% | 9 | Quiet | Low season | |
| 29° | 24° | 20d·340mm | 4.5h | 85% | 9 | Quiet | Low season | |
| 28° | 24° | 17d·230mm | 5h | 84% | 9 | Very busy | Peak |
View Other Months
Koh Samui December Hotel Picks
Frequently Asked Questions
Is December a good time to visit Koh Samui?
Koh Samui in December is moderate. Tourist crowds are very busy and flight/hotel prices are peak.
What's the average temperature in Koh Samui in December?
Koh Samui December averages a high of 28°C and a low of 24°C.
Does it rain much in Koh Samui in December?
Koh Samui December averages 230mm of rainfall over about 17 rainy days.
What should I wear in Koh Samui in December?
Wet season easing late month, but still rainy early on — and cooler than usual. Around 28°C/24°C. Light clothing plus a rain jacket and umbrella; quick-dry fabrics help. Sea ~29°C.
What time are sunrise and sunset in Koh Samui in December?
Koh Samui December sunrise is 06:15 and sunset is 18:10, with 11h 55min of daylight.
What's the air quality like in Koh Samui in December?
Koh Samui December air quality (AQI) averages 36, rated Good. PM2.5 averages 13μg/m³.
What activities are recommended in Koh Samui in December?
In December, Koh Samui is great for Beach days (late month best), Ang Thong/Koh Tao (improving late month), Christmas & New Year on the beach.
Is December peak season in Koh Samui?
Koh Samui December crowds are very busy and prices are peak. Advance reservations are strongly recommended.
Best Months to Visit Koh Samui
View Other Months
Planning a December trip to Koh Samui?
You've checked the weather — next come the budget and the route.
Why you can trust weather guide
Based in Chiang Mai for 8+ years, with 30+ countries visited across Southeast Asia, Japan, and Europe. Every detail in this guide is primary-source verified as of April 2026, with prices auto-refreshed via live exchange rate APIs. This isn't AI-generated boilerplate — it's written from the perspective of someone who has actually been there.