Bhutan is at the same latitude as Miami and Cairo. The climate varies widely depending on the elevation. In the southern border areas it is tropical; at the other extreme, in the high Himalayan regions, there is perpetual snow. Temperatures in the far south range from 15°C in winter (December to February) to 30°C in summer (June to August). In Paro the range is from -5°C in January to 30°C in July, with 800mm of rain. In the high mountain regions the average temperature is 0°C in winter and may reach 10°C in summer, with an average of 350mm of rain.
Rain occurs primarily during the southwest monsoon season from June to September. Bhutan bears the brunt of the monsoon, receiving more rainfall than other Himalayan regions – up to 5.5m a year. During the monsoon, heavy rain falls almost every night; in the day there may be long periods without rain. Low clouds hang on the hills, obscuring views and, if they are too low, forcing the cancellation of flights at Paro airport.
Precipitation varies significantly with the elevation. The average rainfall varies from region to region.
Himalayan regions Less than 500mm per year.
Inner central valleys 500mm to 1000mm per year.
Southern foothills 2000mm to 3500mm per year.
Southern border area 3000mm to 5000mm per year.
When to go
Climate, and therefore season, is certainly a consideration when planning your trip to Bhutan, especially if you are trekking. However, Bhutan’s altitude range, from subtropical valleys to alpine peaks, and its busy festival calendar means you can pretty much visit Bhutan at any time of the year to explore its attractions and witness colourful festivals.
The ideal time for trekking and for travelling throughout the country is autumn, from late September to late November, when skies are generally clear and the high mountain peaks rise to a vivid blue sky. While the climate is best in autumn, in Bhutan an umbrella is usually never far from reach, and no matter when you go, there is likely to be rain periods. Autumn is also the time of the popular Thimphu tsechu (dance festival) and heralds the arrival of the black-necked cranes to their wintering grounds in central and eastern Bhutan. Not surprisingly, therefore, international visitors also peak in autumn, indeed about half of the total annual tourist numbers arrive between September and November. Avoiding the busiest tourist seasons can save you money and hassle.
The winter is a good time for touring in western Bhutan, bird-watching in the south’s subtropical jungles, and whitewater rafting. The days are usually sunny, cool and pleasant, but it’s quite cold once the sun sets and you will need to pack warm clothing. From December to February, there is often snow in the higher regions and occasional snow in Thimphu. The road from Thimphu to Bumthang and the east may be closed because of snow for several days at a time. It would be best not to plan to visit these regions at this time.
Spring, from March to May, is recognised as the second best time to visit Bhutan for touring and trekking. Though there are more clouds and rain than in the autumn, the magnificent rhododendrons, magnolias and other wildflowers are in bloom and birdlife is abundant. You can get occasional glimpses of the high peaks, but these are not the dramatic unobstructed views possible in autumn. Spring is also the time of the magnificent Paro tsechu.
Summer, from June to August, is the monsoon season. And what a monsoon! During these three months 500mm of rain falls in Thimphu and up to a metre falls in the eastern hills. The mountains are hidden, the valleys are shrouded in clouds, and roads disappear in heavy downpours and floods. Summer is still a great time to visit Paro, Thimphu and other parts of western Bhutan. In the mellow monsoon light, the vivid green rice paddies contrast with the dark hills and the stark white dzongs to produce picture-perfect vistas. And the markets are bursting with fresh fruits and vegetables.
A major factor in choosing a time to visit Bhutan, and one that may override considerations of weather patterns, is the festival schedule. These colourful events offer a first-hand glimpse of Bhutanese life and provide an opportunity to see the inside of the great dzongs. It’s possible, and highly recommended, to work at least one festival into a tour or trek program. In recent years overcrowding has become an issue during the major tsechus at Thimphu and Paro, which coincide with the best seasons. At these times flights and accommodation are heavily booked and you may find you need to pay a premium for accommodation or settle for lower-standard accommodation. You stand a much better chance of getting flights, accommodation and probably a more intimate and rewarding festival experience if you schedule your trip around one of the other cultural events.