Cambodia's climate is tropical, with characteristically high temperatures, and two distinct seasons: a monsoon-driven rainy season (May‐October) with south-westerly winds ushering in clouds and moisture that accounts for anywhere between 80-90% of the country’s annual precipitation, and a dry season (November-April), with cooler temperatures, particularly between November and January. Average temperatures are relatively uniform across the country, and are highest in the early summer months before the rainy season begins, when temperatures range between 26-40°C. Temperatures remain between 25-27°C throughout the rest of the year. The wet season arrives with the summer monsoon, in May through November, bringing the heaviest rainfall to the southeast and northwest. Mean monthly rainfall at this time of year can be more than 5000 mm in some areas.
- Mean annual temperatures have increased by 0.8°C since 1960, at a rate of about 0.18°C per decade.
- The rate of increase is most rapid in the drier seasons (December-February and March-May), increasing 0.20‐0.23°C per decade, and is slower in the wet seasons (June-August and September-November), increasing 0.13‐0.16°C per decade.
- Since 1960, the frequency of ‘hot’ days has increased significantly (+46, with strongest increases noted in September- November), as has the frequency of ‘hot’ nights (+63, with strongest increases noted in December-February).
- The frequency of ‘cold’ days has decreased significantly in the September-February period.
- The average number of cold days per year has decreased by 19 (5.2%). This rate of decrease is most rapid in December-February.
- Mean rainfall trends over Cambodia are unclear, with some areas experiencing increases and others decreases, but these changes are not statistically significant.
This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.