Bhutan has a highly diverse climate for a country of its size, primarily due to its varied altitude and the influence of the north Indian monsoons.

The country can be divided into three major physiographic zones: the cold alpine peaks and tundra of the Great Himalayas to the north; the temperate mountain valleys of the Lesser Himalayas in central Bhutan; and the subtropical foothills and floodplains of the Duars Plain in the south.

Thimphu, the capital located in central-west Bhutan, is the only place in the country with a more moderate temperature profile. Winter temperatures in Thimphu typically range from 2°C (35°F) to 12°C (53°F) in January, while summer temperatures in July range from 13°C (55°F) to 19°C (66°F). The northern regions of Bhutan experience extreme cold and generally dry conditions, while the southern regions are marked by extreme heat and significant rainfall.

Bhutan, like eastern Nepal, is affected by the Indian monsoon from late May to mid-September. The country receives more rainfall than other Himalayan regions, with up to 5.5 meters (18 feet) of rain annually during the monsoon season.

The best times to visit Bhutan are either before the monsoon, from mid-March when the winter snow begins to melt off the high passes until the end of May, or after the monsoon, from October to mid-November.

Temperatures can vary significantly depending on elevation, but as a general guideline, temperatures in Thimphu during April/May and October range from around 5°C (41°F) to 25°C (77°F).