The climate can generally be described as tropical. As the country is affected by monsoon, it is hot and humid with an overage temperature around 27.C (80.F). There are two distinct seasons: the Rainy Season and the Dry Season. However, the Dry Season is divided into two sub-seasons, cool and hot. These seasons are:
The Rainy season: From June till October 27-35.C (80-95.f)
The Dry season (cool): From November till February 17-27.C (80-95.F)
The Dry season (Hot) : From March till May 29-38.C (84-100.F)
Temperatures are fairly uniform throughout the Tonle Sap Basin area, with only small variations from the average annual mean of around 25°C. The maximum mean is about 28°C; the minimum mean, about 22°C. Maximum temperatures of higher than 32°C, however, are common and, just before the start of the rainy season, they may rise to more than 38°C. Minimum temperatures rarely fall below 10°C. January is the coldest month, and April is the warmest. Typhoons that often devastate coastal Vietnam rarely cause damage in Cambodia.
The total annual rainfall average is between 100 and 150 centimeters, and the heaviest amounts fall in the southeast. Rainfall from April to September in the Tonle Sap Basin-Mekong Lowlands area averages 130 to 190 centimeters annually, but the amount varies considerably from year to year. Rainfall around the basin increases with elevation. It is heaviest in the mountains along the coast in the southwest, which receive from 250 to more than 500 centimeters of precipitation annually as the southwest monsoon reaches the coast. This area of greatest rainfall, however, drains mostly to the sea; only a small quantity goes into the rivers flowing into the basin. The relative humidity is high at night throughout the year; usually it exceeds 90 percent. During the daytime in the dry season, humidity averages about 50 percent or slightly lower, but it may remain about 60 percent in the rainy period.
The climate in Cambodia is kinder to those who cannot tolerate extreme temperatures. Minimum temperatures rarely fall below 10°C. January is the coldest month, and April is the warmest. Typhoons-tropical cyclones-that often devastate coastal Vietnam rarely cause damage in Cambodia.
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