The Dry Season
October - April/Early May
Cambodia's dry season lasts from October to April, when the dry north-east monsoon arrives, characterised by hot wind blowing across the entire country. Whilst November to January are quite cool (high 20°C's), by April the weather is scorching making early morning and late afternoon Angkor Temple tours, with a few hours by the hotel pool at lunchtime, the preference for many.
Thanks to the hot weather this is unsurprisingly the season when Cambodia's tourist numbers peak.
In more remote parts, such as the north east regions of Mondulkiri & Ratanakiri, the roads are at their best and journey times are shorter because of this. Kep and Sihanoukville on the south coast are popular during this season as they bask in the brilliant sunshine and sea conditions are very favourable.
The Wet Season
Early/Mid May - October
Cambodia's wet season comes courtesy of the southwest monsoon and lasts from May to October, bringing with it almost 75% of Cambodia's annual rainfall. Across Cambodia, throughout much of the rainy season, daytime temperatures average between 25°C and 27°C. The early months of the wet season (May – July) remain very hot with infrequent rainfall usually in the form of short downpours. In the latter months (late July – September) the rains tend becomes more constant and is heavy at times, especially in coastal and rural regions.
Travel in the more remote corners of the country, such as Mondulkiri & Ratanakiri, is almost impossible due to the state of the roads and journeys into the north east are inadvisable during the peak wet season because of this. There is also very limited access to Bamboo Island (near Kep) due to high seas.
On the upside, travelling in monsoonal Cambodia does have its advantages. The dust is gone and the lush greenery of the countryside returns. Angkor Wat in particular is stunning in the wet season, with moats brimming with water and a severe drop in visitor numbers. High rainfall make it the perfect time of year to visit the flooded forests and floating villages of Tonle Sap Lake by boat, as it swells to more than 5 times its size during wet season.