Bhutan faces four distinct seasons:
Spring (March, April and May)
Monsoon/Summer (June, July and August)
Autumn (September, October and November)
Winter (December, January, February and March)
Climate in Bhutan varies depending upon the altitude. The northern part of the country remains colder than other parts of the country. The west and the central part are cool in summer and gets colder towards winter. The eastern part of the country is considerably warm. The southern in the lower belt is hot and humid in monsoon but has pleasant climate in other seasons.
Climate in Bhutan in general remains favorably pleasant through the year. The only wet month where there is substantial rainfall is in mid-June till early September. The hotels here will adequate you with space heaters in your room in cooler times.Air-conditioning is seldom used though a few hotels have it.
Spring and autumn are the best times to visit Bhutan (end of Feb till Mar) and (Sep till Nov).
You can also enjoy the best of wild flowers in May, June and July. This is the time when the nature offers here when mountain slopes are adorned with in plentiful colors.
Nov,Dec, Jan and Feb too provides breath taking views of incredibly beautiful Himalayas during the sunny days.