The ideal time of the year to visit Phnom Penh is during December and January, which are the driest, least humid and coolest months. This coincides nicely with Thailand's climate and these months are the best time of the year to visit both countries. The Water Festival is the biggest festival in the Cambodia calendar and occurs on the full moon in the middle of November.

As with all holidays, the weather can make or ruin the visit, and Phnom Penh's seasonal weather is no exception. Phnom Penh has two main seasons. One is distinctly more favourable to tourists than the other. The tropical dry climate season extends between November and March, while the remainder of the year is classed as a tropical wet climate.

Phnom Penh's weather is surprising as the daytime maximum temperature varies little throughout the year; it is the oppressive humidity that varies wildly. The difference in temperature between the winter months and the summer months is only a few degrees. Phnom Penh is always hot and the intense sun can be very draining. Night time temperatures rarely dip below 20ºC even during the winter months. During the months of March and April the humidity dramatically increases and though classed as the driest season, it makes tourist activities uncomfortable. Phnom Penh has a long wet season, which almost covers half of the year.

The colourful skyline of Phnom Penh

Apart from one exception, the rains of this season are not continuous and an intense downpour can be followed by pleasant weather. Visitors are not encouraged to travel to Phnom Penh during this season due to the unpredictability of the weather, but it is still possible to have a great trip by just avoiding the downpours. September and October are the months to avoid, as this is when the monsoon rains truly hit Cambodia and Phnom Penh.

During this season, rivers become flooded and the inadequate infrastructure cannot cope with the rains. The rains abruptly stop at the beginning of November and this rapid change heralds the beginning of the dry season. The Water Festival signifies the change between the wet season and the dry season with the change of direction of the Tonle Sap River.