The best seasons to visit Bhutan are during Spring (March, April & May) and Autumn (September, October & November). The major bhutanese religious festivals are held during these seasons and fine Spring and Autumn weather makes it an ideal time for trekking in Bhutan and for traveling throughout the country enjoying great views of Himalayan mountains peaks.
Nevertheless, it is possible to visit Bhutan throughout the year as Bhutan has 4 seasons in a year and each season has its own charm as given below:
Spring Season-March, April and May
In Spring the trekking season commences in moderate altitudes. Above 3000 metres spectacular rhododendron forests bloom. It is also the perfect time for a rafting tour. In Paro, one of the largest monastic festivals – Paro tshechu takes place.The temperature is pleasantly mild even up to the Alp regions. Rain comes only in May as the harbinger of the approaching monsoon.
Festivals in Spring:
- Paro Tshechu ( Festival ) : 31st March-4th April 2015
- Bumthang Ura yakchoe Festival : 30th April-4th May 2015
Summer Season- June, July and August
The Summer brings with it the monsoon, but this weather should not deter Bhutan travellers. In the settled areas of the medium ranges of Central and Western Bhutan, pleasant summer temperatures without heat or humidity can be found. Rain falls for short periods daily but is manageable with adequate planning and equipment provided by Bhutan tour Operators / Bhutan travel agents like World Tour Plan. Treks in high mountain areas, e.g. the Snowman Trek, are characterised by mild temperatures, verdant green meadows, and pastures of Blue Poppies and Edelweiss. Nomads tending their yaks in the high Alps are a common sight.
Festivals in Summer:
- Haa Summer Festival from June 30-July 1, 2015
Autumn Season- September, October and November
Autumn is the traditional high season in Bhutan. September and October have the highest number of tshechus (monastic festivals). Trekkers particularly enjoy the clear view of the mountains in October and the low rainfall. Rice harvest means a picturesque landscape remarkable terraces and changing colour.
Festivals in Autumn:
- Thimphu Drubchen: 28th Sept. – 2nd Oct 2015
- Thimphu Tshechu: 3rd to 5th Oct 2015
- Wangdue Tshechu: 23-25, 2015
- Bumthang Thangbi Mani Festival : 29-October 1, 2015
- Bumthang Jambhay Lhakhang Drup: October 29-November 2, 2015
- Bumthang Prakhar Tshechu: October 30-November 1, 2015
Winter Season-December, January and February
In Winter the South beckons. Dry and pleasant conditions make this the best time of year for bird watching in the jungles, village to village trekking in the lower altitudes or a bicycle trip along quiet mountain roads. The trekking routes in the high mountains are covered in deep snow and are impassable at this time of year. The impressive and endangered Black Necked Crane spends the winter in the high valley of Bumdeling (in eastern Bhutan) and Phobjika (in central Bhutan).
Festivals in Winter:
- Trongsa Tshechu from December 21-23, 2015
- Punakha Domchoe from February 15-19, 2015
- Punakha Tshechu from February 20-22, 2015
Text sources by http://www.worldtourplan.com/