Koh Samui Weather in January
Thinking of visiting Koh Samui in January? Expect high temperatures reaching 29°C (84°F) during the day, dropping to 26°C (79°F) at night, and note that quite a bit of rainfall is likely.
Rainfall in Koh Samui in January
You can typically expect 9 days of rain this month, averaging around 81 mm (3.2 in). Rainfall intensity is on the higher side this month. Expect more substantial showers rather than light, passing rain.
Temperature in Koh Samui in January
The perfect temperature in Koh Samui in January makes it a solid month to visit, with 29°C (84°F) during the day and 26°C (79°F) at night. This gives the month a fairly typical daily rhythm, with warmer afternoons and more comfortable nights. At 26°C (79°F) overnight, it stays warm after dark. Light, breathable clothing and good airflow in your room make a noticeable difference.
Sunshine in Koh Samui in January
The days are predominantly sunny, with an estimated total of around 200 hours of sunshine. These sun-filled days are perfect for playing sports, visiting parks, or going for a bike ride.
Average water temperature in January
The water temperature is 27°C (81°F), which most people find very comfortable. A good month for swimming and water sports.If your ideal day consists of dry skies and pleasant temperatures, January and February typically offer the best circumstances for Koh Samui.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Thailand, check out our Koh Samui's climate page.
Koh Samui Temperature in January
Min Temperature
26°C (79°F)
Max Temperature
29°C (84°F)
Water Temperature
27°C (81°F)
Chance of Rain
31%
Precipitation
81 mm (3.2 in)
Rainy days
9 days
Humidity
83%
Sunshine
200 hours
Percentage Sunshine
Daily Historical Temperatures
50-year average (1976-2026)
Based on our historical records, temperatures in Koh Samui typically stay consistent throughout January, with daily highs averaging around 29°C (84°F). Nights are warm, with lows around 25°C (77°F).
Average temperatures in January
Daily Historical Precipitation
50-year average (1976-2026)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in January
Historical weather for Koh Samui in January
Browse day-by-day weather records for Koh Samui spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Koh Samui historical weather extremes in January
Based on weather observations in Koh Samui between 1993 and 2025, these are the recorded extremes during January.
- On January 26, 1999, temperatures climbed to 36°C (97°F), marking the warmest January day on record.
- The lowest daytime temperature in January was 24°C (75°F), recorded on January 23, 2000.
- The coldest night in January in Koh Samui was on January 17, 2023, with a minimum of 21°C (70°F).
Best Places in Thailand in January
Find out more about the weather in Thailand and which places have the best travel conditions in this month. See all of Thailand in January →
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What to Wear in Koh Samui in January
Warm weather calls for comfortable, breathable clothing in January. Cotton t-shirts, shorts, light dresses, and sandals are perfect. You might still want a light layer for evenings or air-conditioned places (for example buses). High rain levels are expected, so pack waterproof gear and an umbrella or poncho. The water temperature sits at about 27°C (81°F), making it perfect for swimming and water activities. Don't forget to pack your favorite swimwear and perhaps some snorkel gear. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.What To Do in Koh Samui in January
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Thailand, check out our Koh Samui's climate page.
Temperature Rainfall Sunshine Humidity Water Temp
See the full Koh Samui climate overview or explore weather in Thailand.
