When to visit Koh Rong (2026 Update)
Last fact-checked: October 2026. Climate figures are long-term averages for nearby Sihanoukville.
HIGH SEASON (DRY)
- Late NOVEMBER to mid-MAY -
This is the most reliable time to visit Koh Rong for beach weather. Skies are mostly sunny, rain is rare and the sea is usually calm and clear, which is ideal for snorkeling, diving and boat tours.
- Dry & Pleasant (Dec - Feb): The most comfortable weather. Daytime highs are around 30-31°C (86-88°F) with lower humidity and a sea breeze. This is peak season, so expect the highest accommodation prices.
- Hot & Dry (Mar - May): The hottest period, with average daytime highs of about 31-33°C (88-91°F), highest in April and May, and rising humidity before the monsoon. Excellent for swimming, but midday jungle trekking can be exhausting.
Travel Tip: Book your ferries and accommodation well in advance if you plan to travel around Christmas, New Year, or the Chinese New Year.
GREEN SEASON (WET)
- Mid-MAY to early NOVEMBER -
Often referred to as the "Green Season," the monsoon months bring higher humidity and frequent rain, but also lush jungle landscapes and spectacular cloud formations. It rarely rains all day.
- Early Rainy Season (mid-May - Jun): Showers become more frequent, typically short and intense in the afternoon or at night, with plenty of sunshine in between.
- Peak Monsoon (Jul - Aug): The wettest time of year. July and August each bring roughly 560-620 mm of rain on average, often in long spells. Sea conditions can be rough, occasionally causing ferry cancellations, and snorkeling visibility drops. The island is much quieter and many resorts offer discounts.
- Late Rainy Season (Sep - Oct): Still wet, with gradually more dry spells towards November. Daytime highs stay around 30-31°C (86-88°F).
Travel Tip: If traveling in the wet season, choose accommodation near the main piers (like Koh Touch or Long Set) to avoid difficult cross-island transfers in rough weather.
Sea Conditions & Plankton Visibility
The sea is calmest from December to April. Koh Rong's famous bioluminescent plankton can be seen year-round, but its intensity varies from night to night. What matters most is darkness: go on a night around the new moon and away from resort lights. Some local guides report the strongest glow in the rainy season, when the water is richer in nutrients, while the dry season offers calmer seas and more comfortable night swims.
Koh Rong Month by Month
Temperatures, rainfall, sea temperature and holidays for every month of the year:
Frequently Asked Questions
What is the best month to visit Koh Rong?
December to February offer the most comfortable weather: sunny, dry, around 30-31°C and with the calmest sea. March and April are also dry, but hotter.
Which is the rainiest month on Koh Rong?
August is the wettest month on average (over 600 mm of rain in nearby Sihanoukville), followed by July, June and September.
Can you swim on Koh Rong all year?
Yes. The sea stays between about 28°C and 30°C all year. In the rainy season the sea can be rough on some days, so swim carefully.