Karāchi, city and capital of Sindh province, southern Pakistan. It is the country’s largest city and principal seaport and is a major commercial and industrial centre. Karāchi is located on the coast of the Arabian Sea immediately northwest of the Indus River Delta.

The impetus to Karāchi’s development originally came from its role as the port serving the Indus River valley and the Punjab region of British India. The development of air travel subsequently increased Karāchi’s importance. It is also the port serving the landlocked country of Afghanistan. Area city, 228 square miles (591 square km); Greater Karāchi, 560 square miles (1,450 square km). Pop. (1998) city, 9,269,265; (2007 est.) urban agglom., 12,130,000.

The 560 square miles that constituted the Federal Capital Area of Pakistan in 1948 are considered, for all practical purposes, to form the Karāchi metropolitan area. Almost half of the area is occupied by the city and its suburbs, and the surrounding 332 square miles consist of agricultural land and wasteland.

Karāchi has pleasant weather for the greater part of the year. May and June are the hottest months, when the mean maximum temperature is about 93 °F (34 °C). Spells of enervating weather occasionally prevail in May and October, during which the temperature shoots up to 105 °F (41 °C). The coolest months are January and February, during which the mean minimum temperature remains about 56 °F (13 °C). A biting north wind occasionally blows in these months, during which the temperature may drop to 40 °F (4 °C). The relative humidity varies from 58 percent in October, the driest month, to 82 percent in August, the wettest month. The average rainfall is 8 inches (203 mm); most of the rain falls during a total of 9 or 10 days in the months of June, July, and August.

The city faces pollution problems. High humidity in the region does not permit evaporation of stagnant water in some places, while fumes from factories and automobiles contribute to air pollution, in spite of land and sea breezes.