Kolkata is tropical wet-dry climate (climate classification Koppen Aw). The average annual temperature is 26.8 ° C (80 ° F), average monthly temperatures range from 19 ° C to 30 ° C (67 ° F to 86 ° F). The summers are hot and humid, with temperatures in the low 30s and during periods of drought maximum temperatures often exceed 40 ° C (104 ° F) during the month of May and June. Winter tends to last for 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). Often, early summer, dust grains followed by spells of thunderstorms and heavy rains lash the city, bringing relief from the humid heat. These are convective storms in nature, and it is locally known as Kal baisakhi, Nor'westers. The rain brought by the Bay of Bengal branch of the monsoon Southwest brunt of the city between June and September, and supplies the city with most of its annual rainfall of 1,582 mm. The highest rainfall occurs during the monsoon in August (306 mm). The city receives 2,528 hours of sunshine each year, with a maximum of sunlight that occur in March. Pollution is a major concern in Kolkata, and suspended particulate matter (SPM) is high when compared to other big cities of India, regularly causing smog and haze. Serious air pollution in the city has resulted in increased pollution-related respiratory diseases such as lung cancer.

Kolkata is the largest sector, the commercial and financial centre of eastern India and the northeast United States. It houses the Calcutta Stock Exchange - India's second largest stock exchange. It is also a major commercial and military port, and the only city in the region to have an international airport. Once India and the main town Capital, Kolkata experienced an economic decline in the years after India's independence due to the frequent unstabilised political condition and increased trade unionism supported by the left wing parties. Between the years 1960 and mid-1990, capital flight huge Was Like many large factories have closed or downsized and companies relocated. The lack of capital and resources associated with a global glut of demand in the city, traditional industries (eg jute) added to the sluggish economy of the city. The liberalization of the Indian economy in the 1990 with the election of a new reformist Chief Minister, Buddhadeb Bhattacharya led to the improvement in the fortunes of the city.

Kolkata's principal business district Until recently, the flexible production has always been the norm in Kolkata, and the informal sector comprises more than 40% of the labour force. State and federal government employees constitute a significant portion of the city workforce. The city has a large unskilled and semi-skilled labour, with other workers and knowledge workers. Kolkata the economic recovery was conducted largely by the IT services, with the IT sector growing by 70% a year - twice the national average. In recent years, there has been a surge in investment in the infrastructure sector housing with a number of new projects coming into the city. Kolkata is home to many industrial units operated by large Indian companies, with products ranging from consumer electronics to jute. Some companies headquartered in Kolkata include ITC Limited, Bata India, Birla Corporation, Coal India Limited, Damodar Valley Corporation, United Bank of India, UCO Bank and Vijaya Bank Allahabad Bank. Recently, various events such as adopting a "Look East" policy of the Government of India, the opening of Nathu La Pass in Sikkim as a road border trade with China and the immense interest in the country of South-East Asia to enter the Indian market and invest Kolkata have put in a position of advantage.