The northern region of the country consists of an arc of Eastern Himalayan alpine shrub and meadows reaching up to glaciated mountain peaks with an extremely cold climate at the highest elevations. Most peaks in the north are over 7,000 metres (23,000 ft) above sea level; the highest point is claimed to be the Kula Kangri, at 7,553 metres (24,780 ft), but detailed topographic studies claim Kula Kangri is wholly in Tibet and modern Chinese measurements claim that Gangkhar Puensum, which has the distinction of being the highest unclimbed mountain in the world, is higher at 7,570 metres (24,840 ft). The lowest point is in the valley of Drangme Chhu, where the river crosses the border with India. Watered by snow-fed rivers, alpine valleys in this region provide pasture for livestock, tended by a sparse population of migratory shepherds.

The Black Mountains in the central region of Bhutan form a watershed between two major river systems: the Mo Chhu and the Drangme Chhu. Peaks in the Black Mountains range between 1,500 and 2,700 metres (4,900 and 8,900 ft) above sea level, and fast-flowing rivers have carved out deep gorges in the lower mountain areas. The forests of the central Bhutan mountains consist of Eastern Himalayan subalpine conifer forests in higher elevations and Eastern Himalayan broadleaf forests in lower elevations. Woodlands of the central region provide most of Bhutan’s forest production. The Torsa, Raidak, Sankosh, and Manas are the main rivers of Bhutan, flowing through this region. Most of the population lives in the central highlands.

In the south, the Shiwalik Hills are covered with dense Himalayan subtropical broadleaf forests, alluvial lowland river valleys, and mountains up to around 1,500 metres (4,900 ft) above sea level. The foothills descend into the subtropical Duars Plain. Most of the Duars is located in India, although a 10 to 15 kilometres (6.2 to 9.3 mi) wide strip extends into Bhutan. The Bhutan Duars is divided into two parts: the northern and the southern Duars. The northern Duars, which abuts the Himalayan foothills, has rugged, sloping terrain and dry, porous soil with dense vegetation and abundant wildlife. The southern Duars has moderately fertile soil, heavy savannah grass, dense, mixed jungle, and freshwater springs. Mountain rivers, fed by either the melting snow or the monsoon rains, empty into the Brahmaputra River in India. Data released by the Ministry of Agriculture showed that the country had a forest cover of 64% as of October 2005.

The climate in Bhutan varies with altitude, from subtropical in the south to temperate in the highlands and polar-type climate, with year-round snow, in the north. Bhutan experiences five distinct seasons: summer, monsoon, autumn, winter and spring. Western Bhutan has the heavier monsoon rains; southern Bhutan has hot humid summers and cool winters; central and eastern Bhutan is temperate and drier than the west with warm summers and cool winters.