Chennai, situated near the 13th north parallel and 80° longitude, stretches its 19km length along the Coromandel Coast. 172sq.km. is covered by its irregular shape. Its highest point is only 60m above sea level. Moreover, it is a low-lying strip of land.
Chennai is located on Eastern Coastal Plains - flat plains, on the southeast coast of India and towards the northeast of Tamil Nadu. Its average elevation is around 6.7m (22ft), whereas its highest point is 60m (200ft). The shoreline of Marina Beach is spread over 12km.
The Cooum River divides the city in half, whereas the river Adyar divides the southern half into two parts, trisecting the city of Chennai. These rivers flow towards the East. A third river, the Kortalaiyar, flows through the northern peripheries of the city before draining into the sea at Ennore. Parallel to the coast, one can see the historic Buckingham canal running almost through the entire length of the city.
The soil of Chennai consists of clay, sedimentary rocks and sandstone. Riverbanks and coasts, such as Tiruvanmiyur, Adyar, Kottivakkam, San Thomes, George Town, Tondiarpet and coastal Chennai have sandy soil. Hence, rainwater percolates quickly through the mud. Cities like T. Nagar, West Mambalam, Anna Nagar, Villivakkam, Perambur and Virugambakkam have clay soil. Guindy, Perungudi, Velachery, Adambakkam and a part of Saidapet have a hard rock.
Several species of birds & animals have acquired a natural habitat formed by a protected estuary on the Adyar River. The Otteri Nullah, an east-west stream, runs through north Chennai and meets the Buckingham Canal at Basin Bridge. Red Hills, Sholavaram and Chembarambakkam Lake supply Chennai with potable water.
Hot, hotter and hottest are the three seasons that are illiberally described by the city. The weather in Chennai is equally hot and humid for eight months, leaving the other four months (November to February). May is the hottest season with the mercury sometimes touching 42°C (107°F). December and January are the coolest months, with a mean temperature of 24°C (75°F). The monsoon is from October to mid-December.
As Chennai lies on the thermal equator, extreme variations in seasonal temperature are prevented. The hottest part of Chennai is, Kathiri Veyyil locally known as Agni Nakshatram (fire star) and its maximum temperature is around 38-42°C (100-107°F). The average annual rainfall is about 1,300mm (51-inches). Chennai also faces Cyclones in the Bay of Bengal.