Bhutan is a mountainous country with some fertile valleys and savanna. Its climate varies greatly: tropical in the southern plains; cold winters and hot summers in central valleys; and severe winters and cool summers in the Himalayas with year-round snow on the main summits. As in most of Asia, the, monsoons dominate the weather patterns, and the altitude and elevation also has a huge impact; hence conditions can vary dramatically from place to place; and day to day.

The three relief zones (the foothills, the Central Himalayan valleys and the High Himalayas) also define three climatic regions: tropical, temperate with monsoon and alpine with monsoon. The southern part of Bhutan is tropical, and in general the east of Bhutan is warmer than the west of the country. Western Bhutan is particularly affected by the monsoons that bring between 60 and 90 percent of the region's rainfall. Mid December to early January can be beautifully clear and dry here. Fluctuations are not so dramatic in summer and daytime temperatures often rise to 30° Centigrade.

In the Thimphu and Paro valleys, daytime temperature in winter averages 20° Centigrade during clear winter days but drops well below freezing during the night with light snowfall and occasional snowstorms. The Punakha and the central valleys tend to be warmer and enjoy a semi tropical climate with very cool winters. The high mountain peaks are snow covered through the year and the mountain passes, especially Thrumsing La (between Bumthang and Mongar), can be treacherous during winter. Bhutan's generally dry spring starts in early March and lasts until mid-April. With splashes of colour everywhere it is supremely multihued and can only be compared to an artist's palette. Summer weather commences in mid-April with occasional showers and continues through the premonsoon rains of late June. The summer monsoon lasts from late June through late September with heavy rains from the southwest. The monsoon weather, its northward progress blocked by the Himalayas, brings heavy rains, high humidity, flash floods and landslides, and numerous misty, overcast days. The views of the Himalayas are completely obscured by clouds and rain from May to August while spectacular rhododendrons bloom in the verdant valleys in this season. Autumn, from late September or early October to late November, follows the rainy season. It is characterized by bright, sunny days and some early snowfall at higher elevations. From late November until March, winter sets in, with frost throughout much of the country and snowfall common above elevations of 3,000 meters. The winter northeast monsoon brings gale-force winds down through High Mountain passes, giving Bhutan its name - Drukyul, which in the Dzongkha language means Land of the Thunder Dragon.