Annual minimum temperature dips in 23 districts: Met officeThe average annual minimum temperature has dipped in 23 districts and the annual maximum temperature has risen in last four decades, the Department of Hydrology and Meteorology (DOHM) says.
The average annual minimum temperature has dipped in 23 districts and the annual maximum temperature has risen in last four decades, the Department of Hydrology and Meteorology (DOHM) says.
The department studied meteorological data over four decades from 1971 to 2014 to conclude the minimum temperature has deviated from normal temperature in 23 districts, while seeing rise in 42 districts.
According to the study, while the average annual maximum temperature of the country has increased by 0.056 degrees Celsius, the minimum temperature has gone down by 0.002 degrees Celsius.
“All Nepal average minimum temperature shows increasing trend annually and in the monsoon season. During other seasons, minimum temperature shows a drop, but they it insignificant,” the report says.
The study shows the minimum temperature has steadily plummeted in Southern plains and other high mountain districts.
The report comes at a time when the cold wave has taken lives and inflicted suffering on residents of Tarai. DOHM Senior Divisional Meteorologist Pratibha Manandhar says, “Most districts in the south show a drop in minimum temperatures particularly during winter.”
Other regions of Nepal, including High Himalayan districts also show a drop in the minimum temperatures.
“However, in Tarai districts, especially during winter season, the mercury drops suddenly from its normal minimum temperature. A drop by few degrees in high Himalayas and the hills is normal, but in Tarai districts the temperature drops by 10 degrees Celsius in winter season,” she said.
While throughout the country, 23 districts witness minimum temperature decrease annually, the number of districts experiencing such decrease increases to 33 during the winter season.
Out of the 33 districts, 14 are north-western districts of Far West and Mid West regions and others are northern parts of Western and Eastern regions show significant decrease in temperatures.
According to Manandhar, the department calculated the fluctuation in minimum temperature after taking the normal temperature of 2010 as the base year.
“The department has observed this trend in the last few years once the cold wave starts. This causes difficulties to people living south of the Siwaliks ranges,” says Manandhar, and adds the minimum temperature shows upward trend in other seasons even in Tarai.
The lowest rise of minimum temperature has been 0.015 degrees Celcius every year in Kathmandu district and highest Mahottari 0.039 degrees Celcius in winter season.
Likewise, the significant highest negative trend, that is decrease, in minimum temperature is observed in Humla district is (-0.076 C/yr) and lowest negative trend is observed in Doti (-0.015 C/yr).
However, the highest increase in minimum temperature was recorded in Dolpa district with 0.046 degrees Celcius per year, which was recorded in monsoon season.
“At physiographic level, Tarai and Siwaliks show significant increasing trend in most of the seasons. High Mountain and High Himalayan regions show decreasing trend in all seasons, except in monsoon. The negative trend is significant only in the winter season in the High Himalayas,” the report concludes.