Climate of Kolkata

Kolkata
Climate chart (explanation)
J F M A M J J A S O N D     17   27 14     23   30 17     33   34 22     48   36 25     102   36 26     260   34 27     332   32 26     329   32 26     296   32 26     151   32 24     17   30 19     7.4   27 14 Average max. and min. temperatures in °C Precipitation totals in mm Source: IMD
Imperial conversion J F M A M J J A S O N D     0.7   80 57     0.9   85 62     1.3   93 71     1.9   97 77     4   97 80     10   93 80     13   90 79     13   90 79     12   90 78     6   89 75     0.7   86 66     0.3   81 58 Average max. and min. temperatures in °F Precipitation totals in inches

Kolkata has a Tropical wet-and-dry climate (Koppen climate classification Aw). The annual mean temperature is 26.8 °C (80 °F); monthly mean temperatures range from 19 °C to 30 °C (67 °F to 86 °F).^[1] Summers are hot and humid with temperatures in the low 30's and during dry spells the maximum temperatures often exceed 40 °C (104 °F) during May and June.^[1] Winter tends to last for only about two and a half months, with seasonal lows dipping to 12 °C – 14 °C (54 °F – 57 °F) between December and January. The highest recorded temperature is 43.9 °C (113 °F) and the lowest is 5 °C (41 °F).^[1] Often during early summer, dusty squalls followed by spells of thunderstorm and heavy rains lash the city, bringing relief from the humid heat. These thunderstorms are convective in nature, and is locally known as Kal baisakhi (কালবৈশাখী, Nor'westers).^[2]

Rains brought by the Bay of Bengal branch of South-West monsoon^[3] lash the city between June and September and supplies the city with most of its annual rainfall of 1,582 mm (62.3 inches). The highest rainfall occurs during the monsoon in August (306 mm). The city receives 2,528 hours of sunshine per annum, with the maximum sunlight occurring in March.^[4] Pollution is a major concern in Kolkata, and the Suspended Particulate Matter (SPM) level is high when compared to other major cities of India,^[5][6] leading to regular smog and haze. Severe air pollution in the city has caused rise in pollution-related respiratory ailments such as lung cancer.^[7]

Climate data for Kolkata (1971–1990)
Month	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Average high °C (°F)	26.4 (79.5)	29.1 (84.4)	33.5 (92.3)	35.3 (95.5)	35.4 (95.7)	34.0 (93.2)	32.3 (90.1)	32.1 (89.8)	32.4 (90.3)	32.3 (90.1)	30.3 (86.5)	27.0 (80.6)	31.7
Average low °C (°F)	13.8 (56.8)	16.9 (62.4)	21.7 (71.1)	25.1 (77.2)	26.0 (78.8)	26.5 (79.7)	26.1 (79.0)	26.1 (79.0)	25.8 (78.4)	23.9 (75.0)	19.6 (67.3)	14.5 (58.1)	22.2
Rainfall mm (inches)	11 (0.43)	30 (1.18)	35 (1.38)	60 (2.36)	142 (5.59)	288 (11.34)	411 (16.18)	349 (13.74)	288 (11.34)	143 (5.63)	26 (1.02)	17 (0.67)	1,800 (70.87)
Avg. rainy days (≥ 1.0 mm)	1.2	2.2	3.0	4.8	8.7	14.7	20.5	20.2	15.7	8.1	1.5	0.9	101.5
Sunshine hours	204.6	203.4	226.3	234.0	226.3	123.0	93.0	105.4	117.0	182.9	192.0	204.6	2,112.5
Source: HKO [8]

References

1. ^ ^{a b c} "Weatherbase entry for Kolkata". Canty and Associates LLC. http://www.weatherbase.com/weather/weatherall.php3?s=090824&refer=&units=metric. Retrieved 2006-04-26. 
2. ^ "kal Baisakhi". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?id=kal-baisakhi1. Retrieved 2006-09-05. 
3. ^ Khichar, M.L.; Ram Niwas (July 14, 2003). "Know your monsoon". Agriculture Tribune, The Tribune. The Tribune Trust. http://www.tribuneindia.com/2003/20030714/agro.htm#2. Retrieved 2007-06-09. 
4. ^ "Calcutta: Not 'The City of Joy'". Gaia: Environmental Information System. http://www.ess.co.at/GAIA/CASES/IND/CAL/CALmain.html. Retrieved 2006-04-26. 
5. ^ Central Pollution Control Board. "Ambient Air Quality in Seven Major Cities During 2002". Ministry of Environment & Forests, Govt of India. Archived from the original on 2006-02-25. http://web.archive.org/web/20060225051501/http://cpcb.nic.in/mcity/m2002.htm. Retrieved 2006-04-26. 
6. ^ Central Pollution Control Board. "Air quality in major cities on 16–17 March 2006". Ministry of Environment & Forests, Govt of India. http://www.cpcb.nic.in/mcity/2006/16_1703/16_1703.htm. Retrieved 2006-04-26. ^{[dead link]}
7. ^ Bhaumik, Subir (17 May 2007). "Oxygen supplies for India police". South Asia (BBC). http://news.bbc.co.uk/2/hi/south_asia/6665803.stm. Retrieved 2007-06-23. 
8. ^ "Climatological Normals of Calcutta, India". Hong Kong Observatory. http://www.weather.gov.hk/wxinfo/climat/world/eng/asia/india/calcutta_e.htm. Retrieved 2011-05-04.