Bangladesh is located in the subtropical monsoon region. Different parts of the country experience different intensities of the seasons. On the basis of the entire climatic condition, Bangladesh can be divided into the following seven distinct climatic zones. A familiar pattern of northwest to southeast isopleths can be seen in this classification.
South-Southeast zone (A)
It includes the Chittagong sub-region and a strip of land extending south of Comilla from the southwest Sundarbans. There is a northeastern climate on hills over 300 meters high. The rest of the area has a small range of temperature, rarely going over a mean of 32°C and below a mean of 13°C. Rainfall is heavy, usually over 2,540 mm. In winter dew fall is heavy.
North-eastern zone (B)
‘This climatic zone includes most of east and south Sylhet and a wedge-shaped strip south of the Meghalaya Plateau. Here too, the mean maximum temperature is rarely above 32°C but the mean minimum is 10°C and below. The average humidity is even more than in the southeastern zone. In this zone winter rain is appreciable. Fog is very common in winter. This is the cloudiest part of Bangladesh. The higher hills and mountains of the Chittagong sub-region can also be classified under this zone.
The northern part of the northern region (C)
Among the climatic zones of Bangladesh, this climatic zone is an area of extremes. In summer the mean maximum temperature is well above 32°C whereas in winter the mean minimum is below 10°C. The summer is dry, with a scorching westerly wind, but the rainy season is very wet, with 2,000 to 3,000 mm of rainfall.
This climatic zone is except that the extremes are less and the rainfall is lower, this zone is similar to northern part of the northern region. The lower rainfall makes this area both atmospherically and pedologically drier.
Western zone (E)
This climatic zone comprises greater Rajshahi district and parts of adjacent districts. This is the driest area in Bangladesh with rainfall generally below 1,500 mm and summer humidity less than 50%. In summer, it is the hottest and driest of all climatic zones. Mean summer maximum temperature is over 35°C.
South-western zone (F)
This climatic zone is the extremes of the climatic zones to the north are somewhat tempered. Rainfall is between 1,500 mm and 1,800 mm. Mean summer maximum temperature is below 35°C. Dew-fall is heavier than in Western climatic zones.
South-central zone (G)
This climatic zone is the zone of rainfall is abundant, being above 1,900 mm. The range of temperature is, as can be expected, much less than to the west, but somewhat more than in South-eastern zone. This is a transitory zone between the South-eastern, North-western and South-western zones and most of the severe hail storms, nor’westers and tornadoes are recorded in this area.
The climatic zones of Bangladesh are used of the prediction of the agricultural production and the predict the natural disater in bangadesh. The climatic zone in the world are linked with the climatic classification in Bangladesh. The monsson in this region is responsible for the himalaya mountain ranges to cause huge rainfall in the downstream of ganguase and bramaputra during the rainly season. The monsson is directly related with the climatic zones of Bangladesh. We can predict the seasonal rainfall beased on the knowledge of the climatic zonation of bangladesh. The Bangladesh is flood prone area. We must know the climatic zones of bangladesh to mitigate the flood risk every year from bangledesh. The mosson are closely related to the flood in the east and north estarn part of Bangladesh. This knowledge can be helpful to mitigate the cyclone (Bhola Cyclone in 1971) and flood disaster in Bangladesh.