September weather forecast
Phnom Penh, Cambodia

September carries forward the monsoon chapter in Phnom Penh with a substantial 249mm (9.8") of rainfall, making it the rainiest month of the year. These showers, although frequent, are usually brief and accompanied by intense bouts of sunshine. The UV index still stands strong at 12, highlighting the persistent sunny weather between showers. The nature of the month’s weather keeps the humidity consistently high, reaching a peak value of 84%. The combination of high temperatures and regular downpours lends a unique vibrancy to the cityscape.

Temperature

The advent of September presents an average high-temperature of a still hot 32.3°C (90.1°F), maintaining a close correlation with the preceding month. In the month of September, the average temperature in Phnom Penh dips to a warm 24.3°C (75.7°F) during the night.

Heat index

During September, the heat index is evaluated at a burning hot 47°C (116.6°F). Precaution: Heat cramps along with heat exhaustion are possible. Heatstroke is a serious risk with continued exertion.
When considering the heat index, it's pivotal to note it is for shade and mild wind conditions. Direct sunlight exposure may result in a rise of the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'feels like', measures the perceived warmth when incorporating the humidity present in the air. An individual's perception of weather can be swayed by a variety of elements including metabolic differences, pregnancy status, and their level of physical exertion. Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely vital to babies and toddlers. Young kids are often more at risk than adults as they tend to perspire less. Besides, their skin surface is larger relative to their small bodies, and their increased heat output from their active lifestyle compounds their risk.
By perspiring, the human body can shed its excessive warmth since evaporated sweat cools it off. Under conditions of high relative humidity, the rate of evaporation decreases. This results in the body retaining more heat than under conditions of dry air. When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat-related illnesses and disorders may develop.

Humidity

The months with the highest humidity are September and October, with an average relative humidity of 84%.

Rainfall

In Phnom Penh, in September, it is raining for 19.8 days, with typically 249mm (9.8") of accumulated precipitation. Throughout the year, there are 153.4 rainfall days, and 1636mm (64.41") of precipitation is accumulated.

Daylight

In September, the average length of the day in Phnom Penh is 12h and 11min.
On the first day of the month, sunrise is at 05:50 and sunset at 18:10. On the last day of September, sunrise is at 05:49 and sunset at 17:51 +07.

Sunshine

With an average of 4.3h of sunshine, September has the least sunshine of the year.

UV index

The months with the highest UV index are February through October, with an average maximum UV index of 12. A UV Index of 11, and more, symbolizes an excessive health risk from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: A maximum UV index of 12 in September translates into the following recommendations:
Take all required precautions, as unprotected skin and eyes can burn in minutes. Limit your direct sun exposure, especially between 10 a.m. and 4 p.m., when UV radiation is strongest. Shade structures might not provide complete sun protection. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes. Directly after swimming or an outdoor workout, generously apply and reapply a broad-spectrum SPF 30+ sunscreen.