Southern Bhutan has a hot, humid sub-tropical climate that is fairly unchanging throughout the year. The temperatures can vary between 15-30 degrees Celsius. In the Central parts of the country the climate cools a bit, changing to temperate and deciduous forests with warm summers and cool, dry winters.
Weather in Bhutan depends upon the altitude. In the northern parts of the country where mountains rise up to 7,000m, weather conditions are similar to arctic. Southwards, closer to India, the weather is hot and humid in the summer and cool in winter. The monsoon rains are usually heavy. Winters can be a good time to visit the lower parts, but then the highest areas are freezing. The best times to visit Bhutan are spring (March-May) and autumn (late September – November) when the weather is warm, dry and sunny but always throw in a couple of warm clothes into your travelling gear when you travel to Bhutan regardless of the season
Bhutan has four seasons:
Spring(March, April and May),
Summer(June, July and August),
Autumn(September, October and November) and
Winter(December, January and February).
Depending on the altitude, the climate varies from semi-tropical to alpine (For every 1,000 m height increase the temperature drops about 7 degree Celsius).
In Southern Bhutan, the climate is tropical in the monsoon season and may range from 15 degree Celsius in winter to 30 degree Celsius in summer.
The east is also warmer than the west.
The centre enjoys sub-tropical climate with very cool winters while the northern parts of the country have harsh climate including snowfall two to three times every winter.
In Thimphu, the capital city, the temperature ranges from -2.5°C in January to 25°C in summer with a rainfall of 100mm. In the high mountain regions the average temperature varies from 0°C in winter to 10°C in summer, with an average of 350 mm of rain.