The climate in Bhutan is varied due to the difference in altitude and the western part of the country is influenced by the north-indian monsoons, which bring 60-90% of the region’s rainfall. The climate varies from subtropical to alpine.
The southern plains and foothills of Bhutan has a subtropical climate which is humid and hot throughout the year. The temperature here sometimes reaches 40 degrees Celsius in the valleys during the summer season. Otherwise, the temperature here fluctuates between 15-30 degrees Celsius. Central Bhutan sees cool, dry winters and warm summers. The west central part of the country has temperatures between 15-26 degrees Celsius during the monsoon, but drops to -4 - 16 degree Celsius during winter .The northern parts of the country, the climate is cold during winter and the mountain peaks are covered in snow throughout the year. The lower regions are also cold in the north due to the high altitude.
Rainfall varies according to area in the country. In the cold northern regions, the rainfall is only about 1.6 inches annually, there is mostly snow. In the temperate central regions, an average of 39 inches of rainfall is received yearly. In the humid, subtropical south, there is an average annual rainfall of 307 inches. From December to February, there is almost no precipitation till March, which sees some rainfall after which the rate of rainfall increases until August, when there is an average rainfall of 25 inches annually.
Bhutan’s spring is in March and summer starts in mid-April, and there are occasional rain showers. The summer monsoon is from June to September and the heavy rains sometimes lead to flash floods, landslides. Late September to late November is autumn, which has bright days and snowfall in higher altitudes. This is followed by winter from November through March, with snowfall in regions above 3000m.
The climate here is tender, and generally warm and temperate. Generally rainfall happens in summer than in winter. The average annual temperature in Thimphu is 11.6 °C. About 1599 mm of precipitation falls annually. In short this place can be enjoyed in any season and any weather.
Rainfall is the time when less number of tourists visit Thimphu, though they miss the natural beauty, when it is at its full peak.
The higher regions are snow covered during winters nevertheless the southern regions and the main valleys are warmer and are tourist prone.
The climate in Punakha is sunny and mild. Köppen-Geiger system has classified the climate here as Cwa. 18.2 °C is the average annual temperature in Punakha. The average rainfall in a year’s time period is 3016 mm.
Punakha is based in the northern part of Bhutan at an elevation of 4,000 meters. Thus, the altitude temperatures being much more pleasant here than in other parts of Bhutan. The city is placed in a fruitful river valley. The city is surrounded by rice fields. Punakha has a cool China characteristic weather with warm and humid summers and cold winters. This exclusive type of climate only appears at high summits at approximately low degree of latitude.
Tsirang lies in the south-central part of the country and the climate here is warm and temperate. The summers in Tsirang receive a good amount of rainfall, while the winters have very little.
The best time to visit Tsirang would be between September to November, when the winters are just about to set in. The winter period is really cold but remains sunny at the same time, offering beautiful blue skies during the daytime.
Phuntsholing has sub-tropical to temperate climates, varying from snowing in winter to 35 degrees in summer. The winters are treacherous here as it is extremely cold and there is persistent snowfall, owing to the fact that it lies in the foothills of the mighty Himalayan range. The roads are often sealed or will be under construction due to the fact that landslides are a common event during the winters, making road travel very dangerous.
The monsoon kicks in Phuntsholing between the months of May and August, when it receives its highest amount of rainfall. The best time to visit the city is during the summer season, when the weather is much warmer and pleasant. This gives rise to the beautiful vegetation in the surroundings, making it an absolute visual treat.
Spring is most widely believed to be the best seasons to visit Paro. The weather is mild and pleasant and offers excellent scenic beauty. Spring is a great time to visit Paro and enjoy the natural surroundings. This is the time of the year when the vibrant flowers in the valley bloom and offer an absolute visual treat. One can also spot many varieties of birds during this season. The clear and blue skies also allow an unobstructed view of the mighty mountains.
The month of September marks the beginning of autumn in Paro, which is also an ideal time to visit the city. The temperature goes up to a maximum 20 degrees and falls to a minimum of 4 degrees. This time of the year is the best to enjoy adventure activities such as trekking. There is a slight possibility of rain during this period, which would to the beauty of the valley.