National Center for Hydrology and Meteorology

Bhutan has observational data available from 1996 to till date which is available in the data repository of the NCHM. A simple data analysis was done on the data period from 1996-2017 over Bhutan from 15 weather stations. The analysis of the 21-year data period revealed that there was an increasing temperature trend over Bhutan. Figure 1 shows the seasonal variation of temperature and rainfall over Bhutan. It shows that Bhutan’s rainfall regime is dominated by summer rainfall. The rainfall during the southwest monsoon season accounts to more than 72 % of the total annual rainfall. Winter season receives the least rainfall with low temperatures recorded. Analysis of number of hot days from selected weather stations are shown in Figure 3. 

Figure 1. Seasonal variation of temperature- maximum (Tmax), minimum (Tmin) and mean (Tavg.) and rainfall (mm) over Bhutan as a whole (based on the stations observation for the period from 1996-2013 for 44 number of stations) (Source: Climatology of Rainfall and Temperature in Bhutan, 2017).



Figure 2. The figures shows the yearly percentage of departure for rainfall (a) and yearly percentage departure for temperature (b) from the normal.



Figure 3. Number of days with a temperature greater than 30° C from observed station data.