The Hindu Kush-Himalayan region - Climate (1/3)
The Hindu Kush-Himalayan climate is principally characterised by the monsoon, a periodic wind, especially in the Indian Ocean and southern Asia. In general the climate is temperate with well-marked seasons. Winter ranges from December to February (both inclusive) and is characterised by snowfall, which is generally heavy and descends lower in the inner valley. Along the main ranges semi-arctic conditions prevail from November to March. March and April are cool and bright, but in the inner valleys snowfalls may occur even during these months. From mid-April the temperature increases rapidly until July.
The rainy season (monsoon) usually begins with occasional showers in June, sets in properly in July, and continues till the middle or end of September. October and November are comparatively dry and the cold weather may start by mid-November. In general tropical rivers show little variation in water temperature, ranging from 18 to 23° C annually. Rivers in alpine regions are much colder and begin to warm up for a short period after the disappearance of their ice-cover in late spring/early summer. Especially rivers that originate from glaciers have extremely cold water near freezing around the year. The monsoon-driven seasonal cycle has significant influence on hydrology of running waters in the HKH regions.