Located in the subtropical zone – south piedmont of Himalayas, the topography in Bhutan is higher in the north and lower in the south and the drastically drop of elevation, together with the influence by the warm and wet flow from the Indian Ocean, there are great differences from place to place. It can be divided into 3 climate zones: north high-clod zone, central temperature zone and south subtropical zone.
North high-cold zone:
Located in the northern part of Bhutan, this area belongs to the great Himalayan high mountain region on average of elevation of 3,000m. It is also called tundra area in which the elevation is over 5,000m, the air pressure is low here with thin air lacked of oxygen, on an annual average of temperature of 1℃ to 4℃. There are over 200 days with temperature below 0℃. 20℃ to 30℃ below zero is frequent here. Annual average rainfall is 300mm to 500mm; every September to the next June is the snowfall season, on an average of 70 days each year with the snow cover reaching 1 to 2 meters, some area may reach 3 meters. It lasts about 10 months of freeze-up period, and there is permanent snow cover in area of elevation of 6,000m. Frequent glaciers shifting are always seen during each June to September. Duration of sunlight lasts long here with strong ultraviolet rays and wind. Although the four seasons is not clear here, there is distinct dry season and wet season. Every October to the next May is dry season with cold weather and gale. Every June to September is wet season with frequent shower and night rainfalls. It is the top limit for agriculture and natural vegetation in those places with the elevation of 5,000m. Both forest line and snowline fluctuate with the precipitation of the rainfall. So the common sight in this kind of area is higher in snowline and lower in forest line.
Generally saying, the land in this region is sterile and poor; people make a living by grazing yaks and sheep, and planting potatoes and barley.
Central temperature zone:
Central temperature zone is mainly based on valleys in central Bhutan, with the elevation 2,000 to 3,000m. Weather is warm and suitable here; the whole year can be divided into four distinct seasons: spring starts from March to May, summer starts from June to August, autumn starts from September to November and the winter lasts from December to the next February. The annual average temperature is 8℃ to 12℃ in this area, summer is the hottest season with the average temperature of 20℃. Autumn is the coolest season all over the year and temperature often fall below zero in winter. The average precipitation of the rainfall in this area is 800 to 2,000mm. There is no distinct rainfall season here, but focus in south slope of Himalayas. Snow season in the mountain area of elevation of 3,000m often starts from the late autumn to the next early summer, on an average snowfall period of 50 days, and the average rainfall precipitation of 150mm. Snow cover may appear somewhere in the mountain areas from November to next April, and it maybe less frequent in the river valley. The average relative humidity are 60% to 70% with heavy rain and roared thunder in spring, regular rainy days in autumn and south wind in each season.
South subtropical zone:
This zone is mainly on basis of south plain and the piedmont hill-area in its south side with the elevation of 1,500m. Climate in this area is hot and humid, often accompanied by heavy rain, which makes it reach the annual precipitation of 2,000 to 5,000. The annual relative humidity is 70% to 80%, while the average temperature is 14℃. There is little snow cover in most places of this region the whole year, and cloudy days are more than sunny days, the number of the latter one is of only 50 days throughout the year. With frequent southerly wind, it can be divided into 3 season in this area: From March to June is summer, hot and torrid, monthly average temperature is 25℃, sometimes reaching 35℃ to 37℃. July to September is rainfall season, since there are frequent heave rains during this period; it makes up 80% of the yearly rainfall. Rainstorms are too often in this area with the top precipitation of 80mm per day, which leads to overflows. Thick fog can be often seen in rainy season and the visibility is poor. Cold season starts from October to the next February, somewhere of the mountain area may fall below zero along with some occasional snowfalls, which leads to the short-period topsoil-freezing. Temperature in both plain and valley is often beyond zero, which makes the vegetation and grain crops be flourishing in this area. Although there is great difference in climate of Bhutan, the four seasons is distinct here: March to May is spring time, June to August is summer, September to November is autumn and the winter is from December to the next February.
Average maximum & minimum temperature list for main parts of Bhutan:
Temperature unit: °C
|
Region
|
Jan
|
Feb
|
Mar
|
Apr
|
May
|
Jun
|
Jul
|
Aug
|
Sep
|
Oct
|
Nov
|
Dec
|
|
Thimphu
|
12.0
3.0
|
16.9
0.5
|
14.0
4.6
|
19.4
9.2
|
19.2
14.5
|
23.7
15.8
|
28.7
17.8
|
24.7
16.7
|
21.4
15.8
|
19.4
11.4
|
16.9
5.8
|
14.7
4.3
|
|
Paro
|
17.0
7.7
|
12.6
3.0
|
13.9
1.6
|
15.1
3.5
|
20.9
12.9
|
23.0
13.1
|
23.5
14.6
|
28.7
14.9
|
23.4
10.7
|
20.4
8.6
|
14.2
3.0
|
11.0
4.3
|
|
Punakha
|
18.0
6.9
|
19.4
6.9
|
23.6
7.8
|
24.9
10.2
|
24.0
10.0
|
21.0
11.1
|
25.8
16.7
|
25.4
11.0
|
26.1
11.5
|
24.6
11.3
|
22.3
12.2
|
23.0
8.9
|
|
Wangdi
|
14.9
6.7
|
20.6
7.3
|
22.6
8.8
|
24.9
12.8
|
28.0
18.0
|
29.0
19.2
|
29.4
20.2
|
28.7
19.9
|
27.5
18.8
|
26.2
16.0
|
23.1
11.5
|
19.4
2.9
|
|
Trongsa
|
10.6
0.3
|
14.1
1.0
|
15.0
0.5
|
17.4
4.4
|
20.0
5.0
|
20.0
13.0
|
20.9
14.6
|
20.0
15.0
|
13.2
13.1
|
20.0
13.1
|
18.5
11.5
|
19.4
2.9
|
|
Bumthang
|
8.5
0.7
|
13.0
0.5
|
16.0
4.5
|
16.1
6.0
|
9.1
8.4
|
20.0
5.0
|
21.3
13.2
|
21.8
14.3
|
21.4
12.7
|
18.7
9.6
|
15.0
2.5
|
14.2
5.0
|
|
Mongar
|
19.9
9.7
|
24.8
10.2
|
27.1
9.5
|
27.5
15.9
|
29.4
20.3
|
30.2
20.9
|
31.0
21.9
|
38.9
34.5
|
30.3
20.4
|
29.2
18.0
|
26.3
12.9
|
24.0
5.7
|
|
Trashigang
|
15.1
3.6
|
17.4
5.0
|
17.7
5.4
|
20.8
8.9
|
20.2
12.4
|
19.1
15.1
|
21.6
6.0
|
22.2
16.4
|
21.3
15.9
|
19.6
11.1
|
16.8
12.9
|
15.7
14.9
|
