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Samui Local Hub

Weather by month

Koh Samui in December 2026

December falls in the Gulf-side rainy season on Koh Samui. Expect heavy showers and windy days, and keep your boat plans flexible.

Live14 Nov, 21:07Advisory:Rough sea forecast for the lower Gulf, 15 Nov: waves 2 m (TMD)

December at a glance

Average high
29.3 °C
Average low
24.0 °C
Rainfall
263 mm
Rain days
11.6 days

58% more rain than an average month

Averages: WMO Climate Normals 1991–2020, Ko Samui (station 48550, Thai Meteorological Department observations), as published on Wikipedia (secondary source, checked 7 Nov 2026). Not a forecast — for warnings use the Thai Meteorological Department. TMD weather warnings

Season verdict

Rainy season — plan indoor options and flexible boat days.

Good for

Spa days, cooking classes, temples, cafés and markets, short drives between showers

Less good for

Snorkeling, long boat trips and anything that needs calm seas

Early vs late December

Rain usually eases through December: November averages 445 mm, December 263 mm and January 127 mm. Later in the month is more often drier, but heavy showers still happen.

Sea & boat trips

Northeast monsoon season: the Thai Meteorological Department issues strong-wave warnings in this period, and ferries or boat trips can be cancelled at short notice. Check the operator on the day.

Tip: when the northeast wind blows, the west and south coasts are often calmer than Chaweng and Lamai on the east side.

Open or closed

Ang Thong Marine National Park usually closes for the season from 1 November to mid-December. The reopening date for 2026 is not confirmed yet — check the park's announcement before you book a trip. Park information

Holidays & alcohol-sale bans in December 2026

No Thai holidays from our list fall in December 2026.

Full holiday calendar · Dates: Bank of Thailand holiday notifications and Thai press; check before you travel.

Events in December

All events →

What to pack

A rain jacket, quick-dry clothes, sandals that grip, a dry bag and some indoor plans.

One next step

Rainy day? A local driver can build a flexible day around the showers — temples, markets, spa, cafés.

Plan a private day

Plan your trip