Koh Rong in December
Last fact-checked: October 2026. Climate figures are long-term averages for nearby Sihanoukville.
December is the start of the high season, with dry, sunny weather and a calm sea.
| Average daytime high | 30 °C |
| Average night-time low | 22 °C |
| Average rainfall | 41 mm |
| Average sea temperature | 28.7 °C |
Long-term averages for nearby Sihanoukville: World Meteorological Organization 1982-2024; sea temperature: seatemperature.org.
Weather
Expect sunny days around 30°C, low humidity and very little rain.
Sea and activities
Calm, clear water makes it ideal for swimming, snorkeling, diving and boat tours.
Holidays and crowds
Christmas and New Year are the busiest time of the year. Book ferries and accommodation well in advance.
Best Beaches & Coast Conditions in December
All beaches around Koh Rong—including 7 km Sok San Beach on the west coast, Lonely Beach in the north, and Long Set on the east—have calm, sparkling turquoise water.
- Recommended Activities: Peak-season scuba diving, snorkeling, kayaking, sunset dining on the sand at Sok San, Saturday Nestival parties on Long Set, and New Year's Eve beach fireworks.
- What to Pack & Booking Tip: Summer beachwear, a light sweater for breezy 22 °C nights, plenty of USD cash, and confirmed hotel reservations.
Koh Rong Weather in December: FAQ
What is the weather like on Koh Rong in December?
December brings picture-perfect tropical weather: sunny blue skies, low humidity, refreshing sea breezes, highs around 30.4 °C, cool 21.9 °C nights, and minimal rain (~41 mm).
How early should I book for Christmas and New Year on Koh Rong?
For stays between December 20 and January 5, book your resort 1 to 2 months in advance and reserve your speedboat ticket at least a week ahead.
Is the sea warm enough for swimming in December?
Absolutely—the Gulf of Thailand around Koh Rong averages 28.7 °C (83.6 °F) in December.