Cambodia has a classic tropical monsoon climate. Temperatures range from 21º C to 35° C, although they can exceed 40 °C in the steamy month of April. There are two distinct seasons. The rainy months are from May to October when the southwest monsoons bring rains from the Gulf of Thailand and the Indian Ocean. It is hot and humid during these months and the heaviest rains kick in between September and October. Total annual rainfall ranges between 100-150cms, with as much as 130-190cms falling in the Tonle Sap and Mekong basins.
Dry Season and Mango Showers
The dry season is from November to March when the northeast monsoon blows. Temperatures can fall to the low 20s in the cool months of December and January when there is little rainfall, low humidity, light breezes and cool evenings. This is peak tourist season for the temples and the beaches. Temperatures creep up in February with short ”mango” showers in the afternoon.
From March to May, the “mango” showers become more frequent and intense in the afternoon. River and lake levels are low and water travel can be difficult. Temperatures peak in April and in inland areas like Siem Reap, they average mid to upper 30ºs C with a more intense sun and rising humidity.
Between June to August, the days are hot and wet, with the predictable afternoon and evening rains lasting for a few hours, providing some relief from the high humidity. Some consider this a desirable time to visit the Angkor temples as the moats and barays are full and the jungles lush and green. Rains are more frequent in the coastal areas and roads can get flooded.
The monsoon rains are still fast and furious in September and are completely over by the end of October. Temperatures hover around the 30ºs C but are not as stifling as in the hot months of April and May.