The weather in Bhutan varies widely depending on what altitude you are at and the various seasons of the year. It is a country that borders the tallest and most magnificent mountain range in the world. The Kingdom of Bhutan also has a river system that is near sea level. If you travel at the right time of year, the weather in Bhutan can be ideal and will give you the most out of your Bhutan travel experience.
Southern Region
The southern region of Bhutan is the flatter part of the country. The temperature and climate are subtropical. During the wintertime in the southern region of Bhutan, the weather is mild because it at a lower altitude and the temperature hovers around 15 degrees Celcius. After wintertime, the climate in Southern Bhutan becomes hot and humid, not the best for travel. The best time for visitors to go to Bhutan would be in the fall months of September through November. This is because the temperature is milder, and it gives tourists a chance to walk through the beautiful scenery that lies in Southern Bhutan.
In the northern region of Bhutan, it is much more mountainous. The eastern part of the Himalayas spread throughout the northern region of Bhutan. Some of the peaks go up to 7000 meters (~21,000 feet). The temperature of the northern region of Bhutan is much milder; it is known for is cold and dry winters. The reason for harsh winters in northern Bhutan is because of the extreme altitude and harsh winds. During the summer it is typically warmer and rainier.
Monsoons
The Bhutan monsoon season is in July through September. Additionally, the monsoons are typically near the southern border of Bhutan. These heavy rainstorms bring approximately 70% of western Bhutan’s rainfall. Precipitation in Bhutan varies widely between the different regions of Bhutan. In the southern region, monsoons and heavy rains occur in the summertime in the rainforest-like environment. Annual precipitation in these parts has gotten up to approximately 7,800 millimeters of rain. This gives the weather of Bhutan rainforests an extremely humid feel.
Additional reading about the weather in Bhutan here!