20-Year Climate Average
Koh Samui, Surat Thani, Thailand Weather in December
Normal High
77°F
Normal Low
73°F
Rainy Days
~21 of the month
Chance of Rain
67%
Humidity
79%
UV index
Not available
Daylight
11.6 hours
Peak wind
13 mph
Usually good for: beaches and outdoor dining.
Based on December climate records from 2006–2025 (Open-Meteo Historical Weather Archive). These are planning averages, not a forecast. Data: Open-Meteo.com, CC BY 4.0.
Current conditions
Forecast versus the climate baseline
81°F
It currently feels like 90°F with 69% humidity, a 70°F dew point and 5 mph wind. Climate averages describe the month; this live reading is what matters for plans today.
82° / 73° · 97% rain
80° / 71° · 100% rain
80° / 72° · 99% rain
Best Months to Visit Koh Samui, Surat Thani, Thailand
Ranked by historical rainy-day frequency — the driest months over the past 20 years.
Methodology
Monthly values use the 2001–2020 observation period. Temperature, precipitation, humidity or dew point, wind, UV and daylight are shown only when the selected source provides them; unavailable fields are never estimated or silently replaced. These are planning normals, not guarantees for a specific trip.
What is the weather like in Koh Samui, Surat Thani, Thailand in December?
The 20-year average high in Koh Samui, Surat Thani, Thailand in December is 77°F, with a low around 73°F and about 21 rainy days.