Phnom Penh weather in September
In September, Phnom Penh has an average high of 30 °C86 °F and an average low of 24 °C75 °F, with about 190 mm7.5 in of precipitation. It is the 9th warmest month of the year and the wettest.
How September compares with other months
Compared with August, September is about the same temperature and wetter by 23 mm0.9 in. Compared with October, September is about the same temperature and wetter by 22 mm0.9 in. Daylight lasts about 12.2 hours around the middle of the month. Average relative humidity is 86% and the average cloud amount 90%.
Is September a good time to visit Phnom Penh?
September is not among the most comfortable months by our comfort score: it is hot (average high 30 °C86 °F), it is fairly wet (190 mm7.5 in) and it is humid (86%). The most comfortable months in Phnom Penh are December.
What to wear in September
For Phnom Penh in September, pack very light, breathable clothing, a sun hat and plenty of water and an umbrella or light rain jacket.
September in nearby places
| Place | High °C°F | Low °C°F | Precip. mmin |
|---|---|---|---|
| Phnom Penh | 3086 | 2475 | 1907.5 |
| Takeo | 3086 | 2475 | 2017.9 |
| Tân Châu | 3086 | 2475 | 2017.9 |
| Hồng Ngự | 3086 | 2475 | 1756.9 |
| Tịnh Biên | 2985 | 2476 | 2158.5 |
| Hòa Thành | 3087 | 2475 | 1716.7 |
| Hà Tiên | 2984 | 2678 | 33013 |
| Long Xuyên | 3086 | 2475 | 1887.4 |
| Trảng Bàng | 3086 | 2475 | 1817.1 |
Other months in Phnom Penh
- January34 °C93 °F / 22 °C71 °F
- February36 °C97 °F / 23 °C74 °F
- March37 °C99 °F / 25 °C77 °F
- April36 °C98 °F / 26 °C79 °F
- May34 °C93 °F / 25 °C78 °F
- June31 °C89 °F / 24 °C76 °F
- July31 °C87 °F / 24 °C75 °F
- August30 °C87 °F / 24 °C75 °F
- September30 °C86 °F / 24 °C75 °F
- October30 °C86 °F / 24 °C75 °F
- November31 °C87 °F / 23 °C73 °F
- December32 °C89 °F / 22 °C71 °F
Frequently asked questions
How warm is Phnom Penh in September?
In September the average high in Phnom Penh is 30 °C (86 °F) and the average low is 24 °C (75 °F).
Does it rain a lot in Phnom Penh in September?
On average about 190 mm (7.5 in) of precipitation falls in September; it ranks 1st of the 12 months.
Is September the warmest month in Phnom Penh?
No. The warmest month in Phnom Penh is March, with an average high of 37 °C (99 °F). The coldest month is December, with an average low of 22 °C (71 °F).
How long is the day in Phnom Penh in September?
In the middle of September the day in Phnom Penh lasts about 12.2 hours from sunrise to sunset. The value is calculated from the position of the city and the sun.
How humid is Phnom Penh in September?
The average relative humidity in September is about 86%. Combined with warm days, it can feel muggy.
How cloudy is Phnom Penh in September?
On average about 90% of the sky is covered by cloud in September. This is the mean cloud amount from satellite data, not the number of sunny days.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.