Land and Resources, Climate

The climate of Bangladesh is of the tropical monsoon variety. In all areas about 80 percent of the annual rainfall typically occurs in the monsoon period, which lasts from late May to mid-October. Average annual precipitation ranges from about 1,400 mm (55 in) along the country’s east central border to more than 5,080 mm (200 in) in the far northeast. In addition to the normal monsoonal rainfall, Bangladesh is subject to devastating cyclones, originating over the Bay of Bengal, in the periods of April to May and September to November. Often accompanied by surging waves, these storms can cause great damage and loss of life. The cyclone of November 1970, in which about 500,000 lives were lost in Bangladesh, was one of the worst natural disasters of the 20th century. Tornadoes, which also accompany the monsoon season, can cause devastation as well.

Bangladesh has warm temperatures throughout the year, with relatively little variation from month to month. January tends to be the coolest month and May the warmest. In Dhaka the average January temperature is about 19°C (about 66°F), and the average May temperature is about 29°C (about 84°F).