Bangladesh - Climate
Bangladesh has a tropical monsoon climate. Annual rainfall is high, averaging from about 119 cm (47 in) up to 145 cm (57 in). There are three distinct seasons. The winter, which lasts from October through early March, is cool and dry, with temperature ranges from 5° C to 22° C (41° F to 72° F ); total winter rainfall averages about 18 cm (7 in) in the east and less than 8 cm (3 in) in the northwest. Temperatures rise rapidly in March, and during the summer season—March through May—average about 32° C (90° F ). Rainfall also increases during this period. However, nearly 80% of the annual rainfall falls from May to September, the monsoon season, when moisture-laden winds blow from the south and southeast. Temperatures drop somewhat, seldom exceeding 31° C (88° F ), but humidity remains high. In April through June and from October through November, tropical cyclones, accompanied by high seas and heavy flooding, are common. There were cyclones in May 1963, May and December 1965, October 1966, and most notably during the night of 12–13 November 1970, when a storm and resultant flooding killed more than 200,000 persons. A cyclone on 30 April 1991 left over 131,000 people dead and nine million homeless. Monsoon floods in 1974, 1980, and 1983 also devastated the country and caused many deaths, and a cyclonic storm on 24–25 May 1985 took more than 11,000 lives. The monsoon in August and September 1988 left three-fourths of the country flooded, 1,300 persons dead, and over three million people homeless, with damage to the country's infrastructure estimated at $1 billion.