Phnom Penh’s climate is generally tropical; therefore, it tends to be hot year-round with minor variations. The average temperature is between 77 to 85 degrees.

In Phnom Penh, there are three basic seasons: the cool season from roughly November to January, the hot season from roughly February through May and the rainy season from roughly June through October. The rainy, monsoon season consists of incessant rainfall. During this time, it is difficult to appreciate all the sights in and around the city as many streets are flooded and muddy.
The summer season especially between February and March is when the weather tends to get scorching hot with unbearable levels of humidity. If visiting at this time, it is a necessity to keep well under the shade as much as possible, wear sun-screen and caps, and carry a big bottle of water. The heat can be very unforgiving especially for those unaccustomed to the weather. Note that most hotels and restaurants are well-cooled, either with air conditioning or with fans. However, not all public or private transportation is so accommodating.

The best time to visit is in the winter, between December and January. During this time, the temperature is cooler but it is still warm and tropical.