We can say all the seasons, months are best time to visit Bhutan.
Bhutan has 4 seasons and each seasons have their own charms and the scenery is more beautiful then one another.
High Season ( March, April, May, September, October & November).
Mid Season (December, January & February ).
Low Season (June, July & August).
Spring in Bhutan is considered the most beautiful time of the year, resplendent and ablaze with a spectacular array of bright colors. This is the time when the valleys are green with fresh vegetation and fruit trees are blossoming – the time when locals are naturally mirthful and cheery; when visitors are most welcome. Also, you can witness the famous Paro tsechu festival.
Autumn is from October to November when it’s generally sunny with some snow at higher elevations. Late November to early March is dry with pre-monsoon showers starting in May. The best time to visit Bhutan is during the spring months of March to May when the valleys come alive with flowers in bloom.
During these months, Bhutan receives more rainfall than any other region in the Himalayas. Glorious sapphire skies and warm weather is a pleasant time to spend visiting places of cultural and historical interest though this season is not the best time for trekking. Enjoy a cup of warm, aromatic tea while watching the rainfall from your hotel window. Or if you possess an adventurous spirit, grab an umbrella/raincoat while it is raining and take a detour through the town!
Winters in Bhutan normally runs from November until late March, and much of the northern area of the kingdom is subjected to colder weather, frost, and snow, especially at elevations above 3,000 meters. The graceful Black-Necked Cranes come to roost at the plain from the Tibetan plateau during this time of the year offering you wild-life picture opportunities. At the Dochula Pass en route to Punakha, you can view the Himalayan peaks including the highest mountain peak in Bhutan – Gangkar Puensum when the weather is clear and sunny as it is during most winter days.
The best time to visit Bhutan ultimately depends on where in the kingdom you want to go and what you want to do.
The country is divided into three climatic zones, between the southern foothills and the Himalayan crest, running from south to north.
1. Tropical: The southern border areas on the foothills
2. Sub-tropical: From the jungles in the southern Bhutan to lower mountains with altitudes of 2000 – 2500 meters
3. Alpine: towards northern high land of the Himalayas