Verdict: Good month
Koh Samui Weather in December
December hits the sweet spot in Koh Samui — highs around 25°C (77°F), ideal for a full day on foot. It's also the wet side of the calendar: rain falls on about 20 days, so build flexibility into plans. Overall, December is a solid month to visit Koh Samui.
Average high
25°C / 77°F
Average low
22°C / 72°F
Rain days
~20
Precipitation
209 mm
What to pack for Koh Samui in December
- Summer clothes, plus one light layer for air-con and evenings
- Rain gear is non-negotiable — expect rain on roughly 20 days
- Comfortable walking shoes — every guide on this site assumes you'll use them
December against the rest of the year
Warmest in Koh Samui: Apr (29°C / 84°F) · Coolest: Dec (25°C / 77°F) · Wettest: Oct (~27 rain days)
26°
22°
Jan
26°
22°
Feb
28°
23°
Mar
29°
24°
Apr
29°
24°
May
29°
24°
Jun
28°
23°
Jul
29°
23°
Aug
27°
23°
Sep
26°
22°
Oct
26°
22°
Nov
25°
22°
Dec
Daily highs / lows in °C · bars show rain days per month · ERA5 climate normals (2020–2024)