Koh Samui weather in January
Temperature, sea and sunshine in January: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in January
Excellent
Best time to visit: January – April
What is the weather like in Koh Samui in January?
In January, Koh Samui is hot: daytime highs average 28 °C, and even at night it stays warm at around 26 °C. The sea averages 27.7 °C – lovely and warm for swimming. The sun shines for around 8 hours a day. Rain is frequent, with about 10 rainy days and 68 mm in total. The air is often humid and muggy. All in all, January is an excellent month for a holiday in Koh Samui.
January compared
How the weather changes from December to February. Tap a month to open it.
| DecemberDec | JanuaryJan | FebruaryFeb | |
|---|---|---|---|
| Score | 74 | 86 | 96 |
| Day | 28° | 28° | 28° |
| Night | 26° | 26° | 26° |
| Sea | 28° | 28° | 28° |
| Sun | 7 h | 8 h | 9 h |
| Rain days | 17 | 10 | 6 |
More details for January
- Daylight
- 11 h 37 min06:40 – 18:18
- UV index
- 9 · very highclear sky, noon (estimate)
- Muggy days
- 30 daysdew point 18 °C or more
- Wind
- 17 km/haverage daily peak
- Cloud cover
- 61 %on average
- Hot days
- 0 days30 °C or more
- Time zone
- UTC+7Asia/Bangkok
How the score comes together
- Temperatureweight 35 %100 %
- Seaweight 25 %100 %
- Sunshineweight 20 %77 %
- Few rainy daysweight 20 %55 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in January
- Swimwear
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- Insect repellent
- Rain jacket or umbrella
Koh Samui in January: quick answers
Is Koh Samui hot in January?
Yes. In January, Koh Samui is hot: daytime highs average 28 °C and nights stay around 26 °C.
Can you swim in Koh Samui in January?
Yes. In January the sea averages 27.7 °C – lovely and warm for swimming.
Does it rain much in Koh Samui in January?
Rain is frequent, with about 10 rainy days and 68 mm in total.
Koh Samui month by month
The whole year in Koh SamuiAll destinations: Thailand
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, GeoNames (CC BY 4.0)