The climate of the country is tropical with a hot and rainy summer and a dry winter. January is the coldest month, with temperatures averaging nearly 26°C (78°F), and April is the warmest month, with temperatures ranging from 33°C to 36°C (91°F to 96°F). Daily temperature ranges from 10°C to 12°C in winter months (December-January) and in the summer months from April to September it varies between 28°C to 40°C. Annual maximum temperature of 1981-2010 increased than that of 1971-2000 notably over the southeastern, the northeastern and the central parts of Bangladesh but it also decreased over the regions of Dinajpur, Mymensingh, Feni and other places.
The study indicates that the highest annual maximum temperature of 0.5ºC is found at Dhaka, Faridpur, Madaripur, Maijdi Court, Cox’s Bazar, Sylhet, Srimongal, Rangpur and Bhola. In the January 2016, the country’s minimum temperature was 12.5 degrees Celsius while the highest at 25.2 degree Celsius. Geographically, Bangladesh is covered with hills at the eastern and the northern parts, where cold and chilly weather prevails much in January. The northern part is on the Himalayan valleys while the southern part in the coast of the Bay of the Bengal. It is a flat low-lying plain, which is located between 20.57ºN to 26.63ºN and 88.02ºE to 92.68E. It is bounded on the west, north and east by India and a common border with Myanmar. Besides, it is situated on the deltas of three large rivers flowing from the Himalayas: the Ganges, the Brahmaputra and the Meghna. In addition, more than 230 major rivers and their tributaries and distributaries crisscross across the country. As a deltaic plain, Bangladesh  experiences  a  wide  range  of  natural  disasters, including floods,  tropical  cyclones,  droughts,  and  tidal  bores  almost  every  year . The  United Nations  Development  Programme  (UNDP, 2008) has  identified  Bangladesh  as  the  most  vulnerable  country  in  the  world  to  tropical cyclones and the sixth most vulnerable to floods.
Bangladesh Meteorological Department (BMD) is a state organization, which uses different categories of cold wave for explaining temperature with three types, including mild cold wave (when minimum temperature lies between 8-10°C), moderate cold wave (when minimum temperature lies 6-8°C) and severe cold wave (when minimum temperature goes below than 6°C) respectively.
In fact, temperature is the lowest in January at all locations. This situation is observed mainly during January and February but it is significant during January only. In January 2016, the number of days having temperature of less than 6°C was the highest at Srimongal (31 days) and then at Ishurdi (28 days) and Rajshahi (25 days). Minimum temperature of almost all the stations (47) shows increasing trends. The significant trends of minimum temperature per hundred years are 3.8°C at Madaripur, 2.6°C at Dhaka, 2.5°C at Rangpur, 2.3°C at Sayedpur, 2.3°C at Maijdi Court, 2.2°C at Cox’s Bazar and 2.1°C at Srimangal & Kutubdia.
The season of winter is commonly distinguished by very light northerly winds, mild temperature, dry weather and cloudy sky with fog over the country.  In January 2017, three type weather patterns may occur at the North, the North-East, the North-West and the central parts of the country. Due to the lowest temperature, mild, moderate and chilly wave was flowing over Rangpur, Mymensingha, Rajshahi, Jushar and Choyadangah on January 15, said Met Office sources. Moderate to thick fog occurred at places over the river basins and light to moderate fog elsewhere over the country during mid night till morning. Mild cold wave was also sweeping over Srimangal, Dinajpur, Dimla, Rajarhat, Tetulia and Sherpur. Night temperature has risen slightly and day temperature remains nearly unchanged over the country till the next two weeks. In addition, weather remains dry with temporary partly cloudy sky over the country having chances of light rain or drizzle at one or two places over Rajshahi and Rangpur divisions.
Cold wave, coming from the north of the Himalaya has been flowing over Bangladesh since January. The result is that temperature is coming down while winter is rising up at different places of the country.  Currently, extreme cold weather has been hampering normal life in the major cities and towns of the country. Especially, winter wave is hampering regular life in the Rajshahi and Rangpur cities for the last few days as the difference between maximum and minimum temperature abnormally fell.  
On 15 January 2017, the lowest temperature was recorded at 05.0 degree Celsius in Tetulia and Rajarhat while the highest at 26.3 degree Celsius in Teknaf in the country, said Met Office source. Due to western disturbance over New Delhi, the temperature was moving up and down in Bangladesh. Aftab Uddin, a met office expert said such a climatic condition may remain in the country for a few days. Temperature also come down in the capital in the last two days due to climate change. Cold is being felt as chilly wave is flowing.  
Mymensingh’s lowest temperature was recorded at 11.8 degree Celsius temperature while the highest 24.7 degree Celsius in the Greater Mymensingh Division in January 2016. Currently, mild cold wave which is blowing over the Sherpur district famous for “Garo Hills” in the last two weeks has paralyzed normal life, said locals.  
All the data for this article that I have collected during the field work of my research indicated that Sherpur is a northern frontier district standing on the valley of the Garo Hills bordering the Maghalaya province of India and on the eastern bank of the old Brahmaputra River. Since all rivers and canals, coming from India flow over the district from the Himalayas, chilly cold and dense fog have covered the entire district where the atmosphere has become foggy and wet, the sun is hardly visible. Being affected with cold chilly wave, the poor have been rushing to the second hand warm cloth shops on different footpaths at the district and upazila levels. Most common warm cloth markets have captured the DC gate, Kharampur, Tera Bazar, New market in the district town, often crowded when January comes very year. Middle class and working class groups are found to buy the warm cloth shops though the prices of warm clothes are higher than the past.
Approximately, 80 percent people in the district are poor who cannot afford to buy warm clothes, said locals. Tribal people, poor farmers, day laborers, fishermen, hawkers, rickshaw pullers are found working bare footed on the streets wearing worm out shirts and Lungies. Domestic animals are also being affected with cold wave. Tribal people are now trying to get rid of chill wave by making fire with dry woods in the hilly areas, said Chairman, Tribal Welfare Association (TWA), adding that they are so poor that they cannot buy warm cloths. Apart from these, the children are being affected by different cold diseases and local hospitals and clinics are found crowded with the parents of the cold affected children. Besides, Department of Agriculture Extension (DAE) has advised marginal farmers about Boro seedbeds if they are damaged by the cold wave and dense fog.  
In this connection, social organizations (ADP world vision) have distributed blankets and warm clothes cost free to the cold affected poor at different places in the district in December last and also in January. Blankets are also distributed from the fund of District Administration of the government, said Deputy Commissioner Dr. AM Parves Rohima, adding that the amount of the warm clothes is very limited in comparison with the demand of the poor people as chilly cold wave and fog are increasing in the district. The local elites are cordially requested to come forward to stand by the poverty stricken people during the winter as they are now badly in need of adequate warm clothes to reduce their sufferings.

The writer us a PhD candidate, Shanghai University, China & Lecturer, Department of English, Haji Jalmamud College, Nakla, Sherpur. Email: [email protected]