Siem Reap weather in September
September is one of the least pleasant months in Siem Reap: highs of 30°C (86°F) and about 231 mm (9.1 in) of rain on average. Nights average 24°C (75°F) and cloud cover 90% (NASA POWER, 2001–2025 averages). It is the wettest month of the year and the coolest. Compared with August, it is about as warm and wetter; October brings highs of 31°C (87°F) and 138 mm (5.4 in) of rain.
Figures are long-term averages for Siem Reap, the largest city in Siem Reap. See below for other places.
Is September a good time to visit Siem Reap?
least pleasant month Weather score 44/100.
September is one of the least pleasant months for weather in Siem Reap. For better conditions, consider Nov–Jan.
Does it rain a lot in Siem Reap in September?
Yes, it is one of the rainy months: about 231 mm (9.1 in) falls in an average September. It is the wettest month of the year.
How warm is Siem Reap in September?
Days average 30°C (86°F) and nights 24°C (75°F).
Siem Reap weather by month
| Month | High | Low | Rain | Cloud | Weather |
|---|---|---|---|---|---|
| January | 33°C (92°F) | 21°C (69°F) | 12 mm | 43% | best |
| February | 36°C (96°F) | 23°C (73°F) | 16 mm | 39% | fair |
| March | 36°C (97°F) | 25°C (77°F) | 46 mm | 61% | fair |
| April | 36°C (96°F) | 26°C (78°F) | 75 mm | 70% | least pleasant |
| May | 34°C (92°F) | 25°C (77°F) | 140 mm | 83% | least pleasant |
| June | 32°C (89°F) | 25°C (76°F) | 168 mm | 86% | least pleasant |
| July | 30°C (87°F) | 24°C (75°F) | 197 mm | 88% | least pleasant |
| August | 30°C (86°F) | 24°C (75°F) | 195 mm | 90% | least pleasant |
| September | 30°C (86°F) | 24°C (75°F) | 231 mm | 90% | least pleasant |
| October | 31°C (87°F) | 23°C (74°F) | 138 mm | 75% | fair |
| November | 31°C (88°F) | 22°C (71°F) | 37 mm | 60% | best |
| December | 32°C (89°F) | 20°C (68°F) | 7 mm | 52% | best |
Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis). Page updated . How we rate months
Weather across Siem Reap in September
Weather can differ a lot within Siem Reap: coasts, hills and mountains each have their own climate.