Siem Reap weather in September
September in Siem Reap: sweltering, soaked, with clean air — one of the weakest months to visit.
#12 of 12 months in Siem Reap · #575 of 604 destinations to visit in September · comfort 48/100 (tier F)
Updated June 2026 · climate normals from ERA5 reanalysis
Siem Reap climate normals — September
| Daytime high | 30°C / 86°F | 🔥 sweltering |
|---|---|---|
| Nighttime low | 25°C / 76°F | |
| Feels like (high) | 36°C / 97°F | |
| Rainfall | 282 mm / 11.1 in | ⛈ soaked |
| Rainy days | 27 days | |
| Humidity | 88% | 💦 very humid |
| Dew point | 25°C / 76°F | |
| Sunshine | 7.5 h/day | |
| Daylight | 12.2 h | |
| Wind | 12 km/h / 7 mph | |
| Air quality (US AQI) | 33 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Siem Reap in September — FAQ
- Is September a good time to visit Siem Reap?
- September in Siem Reap: sweltering, soaked, with clean air — one of the weakest months to visit. It ranks #12 of 12 months for Siem Reap on SeasonMap's comfort score (48/100).
- What is the weather like in Siem Reap in September?
- In September, Siem Reap averages a daily high of 30°C and a low of 24.7°C, with about 281.8 mm of rain over roughly 27 rainy days.
- What is the air quality in Siem Reap in September?
- Siem Reap has a mean US Air Quality Index of about 33 in September.