The climate in Bhutan is extremely varied. This variation in the climatic conditions and average temperature can be attributed to two main factors, the vast differences in altitude present in the country and the influence of the north Indian monsoons.
Southern Bhutan has a hot, humid sub-tropical climate that is fairly unchanging throughout the year. Temperatures can vary between 15-30 degrees Celsius. In the Central parts of the country, the climate cools a bit, changing to temperate and deciduous forests with warm summers and cool, dry winters. In the far Northern reaches of the kingdom, the weather is cold during winter. Mountain peaks are perpetually covered in snow and lower parts are still cool in summer owing to the high altitude terrain.
The Indian summer monsoon lasts from late-June through late-September and is mostly confined to the southern border region of Bhutan. It brings heavy rain and high humidity, to the southern region. These rains bring between 60 and 90 percent of the western region’s rainfall.
Annual precipitation ranges widely in various parts of the country. In the northern border region to Tibet gets about forty millimeters of precipitation a year which is primarily snow. In the temperate central regions, a yearly average of around 1,000 millimeters is more common, and 7,800 millimeters per year has been registered at some locations in the humid, subtropical south, ensuring the thick tropical forest, or savanna.