24 September
Constitution Day
Official public holiday, observed nationwide.
Month by month
Cambodia in September
The wettest month of the year, and the greenest, emptiest, cheapest Cambodia you will ever see. September is for the unhurried.
- Siem Reap highs
- ~31°C
- Rainy days (SR)
- 27
- Crowds
- Moderate
- Public holidays
- 1
The short answer
What September is really like
September peaks the monsoon: around 318 mm in Siem Reap and 297 mm in Phnom Penh, with rain possible at any hour, not just the classic afternoon slot. Rural roads get muddy, some island boats stop, and humidity sits high.
The reward is absolute low season: near-empty temples under dramatic skies, rock-bottom rates, and the Tonlé Sap swelling toward its annual maximum, with the flooded-forest villages at their most extraordinary. This is the connoisseur’s month, not the beginner’s.
The numbers
September weather, destination by destination
Ten-year averages, not brochure promises: computed from the same ERA5 climate dataset that powers our weather tool.
| Destination | Avg. daily high | Rainfall | Rainy days |
|---|---|---|---|
| Siem Reap | 31°C | 318 mm | 27 |
| Phnom Penh | 31°C | 297 mm | 28 |
| Battambang | 31°C | 267 mm | 27 |
| Kampot | 29°C | 234 mm | 26 |
| Kep | 29°C | 279 mm | 27 |
| Koh Rong (islands) | 28°C | 520 mm | 28 |
| Mondulkiri | 26°C | 318 mm | 29 |
International crowds this month
Moderate, September ranks level 2 of 4 for international arrivals in the Siem Reap region (quartiles on Ministry of Tourism monthly data).
Dates that shape the month
Holidays & festivals in September
Our picks
Where to go in September
Tonlé Sap floating villages
The lake approaches its high-water peak: stilt houses become true islands and boats replace every road. The single best month to see it.
From Siem ReapAngkor, empty
The quietest the great temples get. Between showers the light is extraordinary: bring shoes that forgive mud.
Temple guidePhnom Penh museums & cafés
The capital’s indoor culture carries the month: the National Museum, galleries, and the best café scene in the country.
Best cafésPractical
Tips for September
- Accept that some days will simply be wet, build museum, spa and café time into the plan.
- Waterproof shoes or sacrificial sandals: temple paths and village lanes are muddy.
- Pchum Ben preparations begin: pagodas grow busy and atmospheric ahead of the October dates.
- Skip the islands; this is their wettest month (over 500 mm on Koh Rong).
Good to know
Frequently asked questions
Is September the worst month to visit?
It is the wettest, but "worst" depends on what you came for. Sightseeing needs flexibility; in exchange you get the year’s lowest crowds and prices, and the Tonlé Sap at its most spectacular.
Do things close in September?
Cities and Siem Reap run normally. The practical closures are maritime: some island boats and beach operations pause for the rough-sea season.
Why visit in September at all?
The flooded forest at high water, empty world-class temples, monsoon skies, and hotel rates that can be less than half of January’s. For return visitors it is a favourite.
Continue planning
More Cambodia travel info
Visa & Entry Requirementse-Visa, visa on arrival, e-Arrival card and entry rules.How Many Days & Itineraries3 days to 2 weeks: routes that actually work.Festivals & Public HolidaysOfficial holiday dates: Khmer New Year, Water Festival…Money & PaymentsDollars, riel, KHQR, ATMs and tipping.Getting AroundBuses, boats, flights, trains and city transport.What’s happening todayConcerts, markets, exhibitions and things to do this week.
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