Spring and Autumn are the peak times for trekking and sightseeing. The skies are usually clear and the weather fine. The best months are March to May and late September to November. April and October are the most popular months for tourism-
December to February is also a good time to visit Bhutan. However the weather will be colder and some of the high passes may be closed due to snowfall. Nights are cold and require heavy woolen clothing. The foothills of Bhutan are also very pleasant during the winter.
The climate varies with altitude, with the highest temperatures and rainfall occurring in the south which bears the brunt of the monsoon between June and September. During summer, clouds can obscure the fine views but this is an ideal time for botanists to visit the high valleys when the wildflowers are in full bloom.
Temperatures drop dramatically with increases in altitude so it is advisable if touring around Bhutan to have suitable clothing for all weather.