Climate averages 1991–2020
Siem Reap weather
in September.
A hot, very wet month: the 9th warmest and the wettest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a hot month in Siem Reap: daytime highs average 30.3°C and nights cool to about 24.5°C. By daytime temperature it is the 9th warmest of the 12 months.
Expect about 244 mm of rain on roughly 26 days, which makes September a very wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 12 h 13 min on an average September day.
The nearest other city in this atlas is Battambang (77 km away). In September its highs average 31.2°C, 0.9°C warmer than Siem Reap, with 192 mm of rain.
Among the 8 cities listed in Cambodia, Siem Reap ranks 6th of 8 for the warmest September highs and 5th of 8 for the driest September (rainfall, lowest first). The mean September high of those 8 cities is 30.4°C; Siem Reap is 0.1°C cooler than that mean.
From September to October, average highs fall by 0.3°C to 30.0°C, and monthly rainfall falls from 244 mm to 224 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Siem Reap climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 31.3°C21.9°C | 21.9°C | 9.0 | 1.9 | 11.411 h |
| February | 32.8°C23.5°C | 23.5°C | 13 | 2.6 | 11.712 h |
| March | 34.1°C25.4°C | 25.4°C | 52 | 7.8 | 12.012 h |
| April | 34.2°C26.1°C | 26.1°C | 94 | 13.4 | 12.412 h |
| May | 33.0°C26.1°C | 26.1°C | 148 | 21.4 | 12.713 h |
| June | 32.0°C25.7°C | 25.7°C | 131 | 20.7 | 12.913 h |
| July | 31.3°C25.3°C | 25.3°C | 135 | 22.0 | 12.813 h |
| August | 31.0°C25.1°C | 25.1°C | 162 | 24.3 | 12.613 h |
| September, selected | 30.3°C24.5°C | 24.5°C | 244 | 25.9 | 12.212 h |
| October | 30.0°C23.8°C | 23.8°C | 224 | 23.2 | 11.812 h |
| November | 30.1°C22.8°C | 22.8°C | 62 | 8.8 | 11.512 h |
| December | 30.1°C21.7°C | 21.7°C | 16 | 2.9 | 11.411 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Battambang in SeptemberCambodia · 77 kmHigh 31.2°C · Low 24.5°C · 192 mm rain
- Paoy Paet in SeptemberCambodia · 144 kmHigh 30.0°C · Low 24.0°C · 237 mm rain
- Kampong Chhnang in SeptemberCambodia · 151 kmHigh 30.8°C · Low 24.5°C · 234 mm rain
- Chanthaburi in SeptemberThailand · 208 kmHigh 28.7°C · Low 24.5°C · 363 mm rain
- Phnom Penh in SeptemberCambodia · 231 kmHigh 31.0°C · Low 24.5°C · 245 mm rain
- Ubon Ratchathani in SeptemberThailand · 234 kmHigh 29.9°C · Low 23.8°C · 273 mm rain
- Dangkao in SeptemberCambodia · 234 kmHigh 31.0°C · Low 24.5°C · 245 mm rain
- Kabin Buri in SeptemberThailand · 241 kmHigh 29.7°C · Low 23.6°C · 283 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Siem Reap) is explained once on the Siem Reap year overview and on the Sources, method and limits page.