Warm
Average highs sit around 29°C, giving warm days by monthly-average standards.
December verdict
Koh Samui, Thailand in December
Weather score66Good
Good for holiday weather
Average highs sit around 29°C, giving warm days by monthly-average standards. Sunshine averages 6.5h per day, enough for a balanced month. Rainfall averages 188mm, so showers are a real planning factor.
December weather
Monthly averages
Temp
29°C
Rain
188mm
Sun
6.5h
Sea
28°C
Weather score
66
Good
Seasonal climate calendar
TemperatureTemp
RainRain
SunSun
SwimSwim
Weather scoreWeather score
Trip feel
Wet
Rainfall averages 188mm, so showers are a real planning factor.
Some sun
Sunshine averages 6.5h per day, enough for a balanced month.
Warm sea
Sea temperatures average 28°C, so swimming is usually comfortable by monthly-average standards.
Map
Weather map
Compare Koh Samui, Thailand with nearby places by weather score, rain, sun, temperature, and swim conditions.
Temperature
December29°C average high
December is cooler than the yearly average, which can make sightseeing feel gentler than in hotter months.
Warmest monthsApril to September
This stretch sets the upper range for average daytime heat.
Rain
December188mm average rain
December sits near Koh Samui's yearly rainfall average, so rain is a normal planning factor rather than an outlier.
Driest monthsJanuary to September
This is the drier part of the year, when outdoor plans usually need less weather flexibility.
Sun
December6.5 hours average sun
December sits close to Koh Samui's yearly sunshine average, so it is a middle-of-the-pack month for bright days.
Brightest monthsFebruary to April
This stretch has the strongest sunshine in the monthly averages.
Sea temperature
December28°C average sea
December is one of the cooler sea months locally, though the water still averages warm enough for most swimmers.
Warmest seaApril to September
Sea temperatures are usually near 30°C in this stretch, so swimming comfort is at its strongest.
Weather score
December66 weather score
December sits close to Koh Samui's yearly weather-score average, giving a typical overall read on the month.
Best weather monthsFebruary to March
These months have the strongest weather score in the monthly averages.
