Koh Samui Weather in December
Koh Samui in December averages 29°C (84°F) during the day and 26°C (79°F) at night. Keep in mind that quite a bit of rainfall is expected this month.
Rainfall in Koh Samui in December
Historically, approximately 14 days this month are expected to have rain, averaging 150 mm (5.9 in). When showers do arrive, they tend to be on the heavier side. Worth being prepared even if rain days are not that numerous.
Temperature in Koh Samui in December
December in Koh Samui brings high temperatures, with highs of 29°C (84°F) and nights around 26°C (79°F). This kind of day-to-night contrast is typical for this time of year. With lows of 26°C (79°F), it stays warm throughout the night. A cold shower before going to sleep is one of the easiest ways to cool down before bed.
Sunshine in Koh Samui in December
The area enjoys a balanced 177 hours of sunlight, ensuring it's neither too overcast nor too sunny.
Average water temperature in December
At 29°C (84°F), the water feels bath-warm. Fine for swimming, but those looking for a cooling swim may be a bit disappointed.Our weather planner can help you find worldwide destinations with pleasant weather during this period. January and February typically offer the best weather 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 December
Min Temperature
26°C (79°F)
Max Temperature
29°C (84°F)
Water Temperature
29°C (84°F)
Chance of Rain
45%
Precipitation
150 mm (5.9 in)
Rainy days
14 days
Humidity
82%
Sunshine
177 hours
Percentage Sunshine
Daily Historical Temperatures
48-year average (1976-2025)
Based on our historical records, temperatures in Koh Samui typically stay consistent throughout December, with daily highs averaging around 29°C (84°F). Nights are warm, with lows around 25°C (77°F).
Average temperatures in December
Daily Historical Precipitation
48-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in December
Historical weather for Koh Samui in December
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 December
The extremes listed below come from historical weather data collected in Koh Samui from 1986 through 2025.
- The warmest day in December was on December 11, 2023, with a maximum of 34°C (93°F).
- Koh Samui experienced its chilliest December day on December 25, 1999, reaching only 24°C (75°F).
- The coldest night in December in Koh Samui was on December 21, 1999, with a minimum of 20°C (68°F).
Best Places in Thailand in December
Find out more about the weather in Thailand and which places have the best travel conditions in this month. See all of Thailand in December →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in Koh Samui in December
Warm temperatures in December make for comfortable sightseeing weather. Pack breathable fabrics like cotton shirts, knee-length shorts or skirts, and comfortable walking shoes. A thin long sleeve for indoor spaces is handy. Heavy rain is guaranteed, please bring a good poncho and waterproof everything! Expect water temperatures of around 29°C (84°F), which is ideal for taking a refreshing dip. Bring swimwear and consider packing a towel for drying off. Sunglasses could come in handy during the sunnier parts of your trip.What To Do in Koh Samui in December
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.
