Climate of Dhaka

Dhaka experiences a hot, wet and humid tropical climate. Under the Köppen climate classification, Dhaka has a tropical wet and dry climate. The city has a distinct monsoonal season, with an annual average temperature of 25 °C (77 °F) and monthly means varying between 18 °C (64 °F) in January and 29 °C (84 °F) in August.[1] Nearly 80% of the annual average rainfall of 1,854 millimetres (73.0 in) occurs during the monsoon season which lasts from May until the end of September.[1] Increasing air and water pollution emanating from traffic congestion and industrial waste are serious problems affecting public health and the quality of life in the city.[2] Water bodies and wetlands around Dhaka are facing destruction as these are being filled up to construct multi-storied buildings and other real estate developments. Coupled with pollution, such erosion of natural habitats threatens to destroy much of the regional biodiversity.[2]

Cold weather is unusual in and around Dhaka. When temperatures decrease to 8 °C (46 °F) or less, people without warm clothing and living in inadequate homes may die from the cold.[3][4][5]

Factors

Dhaka has a tropical wet and dry climate. The monsoon season brings nearly 80% of the annual average rainfall of 1,854 millimeters (73 in) occurs between May and September.[6]

  • Southwest Monsoon occurs from June till September during the summer months. During this period very heavy rainfall lashes the city as well as the entire country. Flash floods are common in Dhaka almost every year.
  • Tropical Storms do occur during the summer months from April till June and then from September till December. These cyclones occur almost every year in Bangladesh though their intensity varies from year to year.
  • Tornadoes are fairly common in Bangladesh as it is one of the most frequently hit countries in the world, behind the United States and Canada.[7]

Impact of climate change

Climate change has forced many people of Bangladesh living in rural areas to migrate to cities that has caused a sharp rise in the slum population of Dhaka.[8] As Bangladesh is already less than 20 feet above sea level, thus there are fears that by the end of the 21st century, more than a quarter of the country will be inundated and 15 million people will be displaced.[8] The population of Dhaka, currently 13 million people, is projected to increase to 20 million by the year 2025. This raises fears of water-borne diseases and outbreaks of several other diseases.[9] While a UN and WWF report warned that Dhaka tops the risk of climate change in Asia.[10]

Monsoon rainfall of Dhaka

The Monsoon season begins from June till September. The following is the annual monsoon rainfall for the last few years based on data from the Bangladesh Meteorological Department.[11]

  • In 2000, a total of 5,220 millimetres (206 in) was recorded.
  • In 2001, a total of 5,590 millimetres (220 in) was recorded.
  • In 2002, a total of 7,257 millimetres (285.7 in) was recorded.
  • In 2003, a total of 4,934 millimetres (194.3 in) was recorded.
  • In 2004, a total of 8,308 millimetres (327.1 in) was recorded.
    Flooded street in Dhaka during the monsoon rains of 2004
  • In 2005, a total of 6,903 millimetres (271.8 in) was recorded.
  • In 2006, a total of 7,137 millimetres (281.0 in) was recorded.
  • In 2007, a total of 8,895 millimetres (350.2 in) was recorded.
  • In 2008, a total of 6,712 millimetres (264.3 in) was recorded.
  • In 2009, a total of 6,252 millimetres (246.1 in) was recorded.
  • In 2010, a total of 5,016 millimetres (197.5 in) was recorded.

Extreme weather events

Extreme weather events include tropical cyclones, tornadoes, cloudburst and flash floods.

  • In 1956, about 326 millimetres (12.8 in) of rain was recorded in 24 hours in Dhaka.[12]
  • In 1970, a Category-3 tropical cyclone killed 500,000 people.[13]
  • In 1989, a tornado killed 1,300 people in Dhaka Division.[14]
  • In 1991, a Category-5 tropical cyclone killed 138,866 people in the country.[15]
  • In 2004, a record-breaking 341 millimetres (13.4 in) mm of rain was recorded in Dhaka in 24 hours.[12]
  • In 2009, about 333 millimetres (13.1 in) of rain was recorded in Dhaka in 24 hours.[12]

Statistics
Climate data for Dhaka
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °C (°F) 31.1
(88.0)		 34.4
(93.9)		 40.6
(105.1)		 42.2
(108.0)		 41.1
(106.0)		 36.7
(98.1)		 35.0
(95.0)		 36.1
(97.0)		 36.7
(98.1)		 37.2
(99.0)		 34.4
(93.9)		 30.6
(87.1)		 42.2
(108.0)
Average high °C (°F) 25.4
(77.7)		 28.1
(82.6)		 32.5
(90.5)		 33.7
(92.7)		 32.9
(91.2)		 32.1
(89.8)		 31.4
(88.5)		 31.6
(88.9)		 31.6
(88.9)		 31.6
(88.9)		 29.6
(85.3)		 26.4
(79.5)		 30.6
(87.1)
Daily mean °C (°F) 19.1
(66.4)		 21.8
(71.2)		 26.5
(79.7)		 28.7
(83.7)		 28.7
(83.7)		 29.1
(84.4)		 28.8
(83.8)		 29.0
(84.2)		 28.8
(83.8)		 27.7
(81.9)		 24.4
(75.9)		 20.3
(68.5)		 26.1
(79.0)
Average low °C (°F) 12.7
(54.9)		 15.5
(59.9)		 20.4
(68.7)		 23.6
(74.5)		 24.5
(76.1)		 26.1
(79.0)		 26.2
(79.2)		 26.3
(79.3)		 25.9
(78.6)		 23.8
(74.8)		 19.2
(66.6)		 14.1
(57.4)		 21.5
(70.7)
Record low °C (°F) 6.1
(43.0)		 6.7
(44.1)		 10.6
(51.1)		 16.7
(62.1)		 14.4
(57.9)		 19.4
(66.9)		 21.1
(70.0)		 21.7
(71.1)		 21.1
(70.0)		 17.2
(63.0)		 11.1
(52.0)		 7.2
(45.0)		 6.1
(43.0)
Average precipitation mm (inches) 7.7
(0.30)		 28.9
(1.14)		 65.8
(2.59)		 156.3
(6.15)		 339.4
(13.36)		 340.4
(13.40)		 373.1
(14.69)		 316.5
(12.46)		 300.4
(11.83)		 172.3
(6.78)		 34.4
(1.35)		 12.8
(0.50)		 2,148
(84.57)
Average precipitation days 2 3 5 10 15 14 17 16 13 7 2 1 105
Average relative humidity (%) 71 64 62 71 76 82 83 82 83 78 73 73 75
Mean monthly sunshine hours 220.3 225.3 256.3 237.8 220.9 142.2 131.5 140.6 152.7 228.6 236.3 242.6 2,435.1
Source 1: Bangladesh Meteorological Department[16][17][18][19][20]
Source 2: Sistema de Clasificación Bioclimática Mundial (extremes 1934–1994),[21] Deutscher Wetterdienst (sun, 1961–1990)[22][23]

References
  1. "Weatherbase: Historical Weather for Dhaka, Bangladesh". weatherbase.com. Retrieved 2008-12-15.
  2. Mondal, M. Abdul Latif (2006-09-27). "Our Cities: 15th Anniversary Special". The Daily Star. Archived from the original on 2007-03-02. Retrieved 2006-09-27.
  3. "Cold Wave Kills 102 People in Bangladesh". Los Angeles Times. January 6, 1995. p. 6. Retrieved February 4, 2015. Temperatures plunged to 39 degrees this week in northern Bangladesh, killing people too poor to afford jackets or sweaters. It was the lowest temperature recorded in Bangladesh since 1964, when the temperature dropped to 38 degrees.
  4. "33 in Northern Bangladesh Are Reported Killed by Cold". The New York Times. Associated Press. December 29, 1989. p. A3. Retrieved February 4, 2015. A cold wave in normally tropical northern Bangladesh has killed at least 33 people in the last week, a newspaper reported today. Temperatures in the region have hovered around 42 degrees Fahrenheit since Monday, and the newspaper said the victims were laborers and other poor people who were unable to protect themselves from the cold.
  5. "Hundreds Dead in Bangladeshi Cold Spell". The Washington Post. 6 January 1998. p. A14. In northern Bangladesh, temperatures dipped to 46 degrees Sunday, the Independent newspaper said. Although the temperature was above freezing, it was cold enough to kill people in tropical Bangladesh, where half the population of 120 million people can't afford enough food or warm clothes.
  6. "Dhaka, Bangladesh Travel Weather Averages (Weatherbase)".
  7. "The Online Tornado FAQ (by Roger Edwards, SPC)".
  8. "Climate migration drives slum growth in Dhaka". Archived from the original on 2012-03-13. Retrieved 2010-11-19.
  9. "Case study: Dhaka's extreme vulnerability to climate change - PreventionWeb.net".
  10. Fogarty, David (2009-11-12). "Dhaka tops risk table in Asia climate threat study". Reuters.
  11. "Bangladesh Meteorological Department". Archived from the original on 2011-02-19. Retrieved 2010-11-19.
  12. "'Cloud Burst' Breaks 53-year Record". Archived from the original on 2018-03-12. Retrieved 2010-11-20.
  13. "NOAA Researcher's Warning Helps Save Lives in Bangladesh". Archived from the original on 2008-05-17. Retrieved 2010-11-20.
  14. "Bangladesh Tornado Climatology".
  15. http://www.swissre.com/resources/dd6346004d4e9669ac76eecedd316cf3-sigma2_2009_e.pdf%5B%5D
  16. "Monthly Maximum Temperature". Bangladesh Meteorological Department. Retrieved 26 April 2018.
  17. "Monthly Minimum Temperature". Bangladesh Meteorological Department. Retrieved 26 April 2018.
  18. "Normal Monthly Rainfall". Bangladesh Meteorological Department. Retrieved 26 April 2018.
  19. "Normal Monthly Rainy Day". Bangladesh Meteorological Department. Retrieved 26 April 2018.
  20. "Normal Monthly Humidity". Bangladesh Meteorological Department. Retrieved 26 April 2018.
  21. "Bangladesh – Dacca" (PDF) (in Spanish). Centro de Investigaciones Fitosociológicas. Retrieved 23 February 2013.
  22. "Station 41923 Dhaka". Global station data 1961–1990—Sunshine Duration. Deutscher Wetterdienst. Archived from the original on 17 October 2017. Retrieved 26 April 2018.
  23. "Station ID for Dhaka is 41923". Archived from the original on 2017-10-17. Retrieved 2018-04-26.
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