Kottayam has an average elevation of 3 metres (9 feet) from sea level. Kottayam is situated in the basin of the Meenachil River and in the basin of the Vembanad backwaters, which are formed from several streams in the Western Ghats in Idukki district. It flows through Kottayam district and joins Vembanad lake. According to the division of places in Kerala based on altitudes, Kottayam is classified as being a midland area. The general soil type is alluvial soil. The vegetation is mainly tropical evergreen and moist deciduous type.
The climate in this district is moderate and pleasant. Kottayam's proximity to the equator results in little seasonal temperature variation, with moderate to high levels of humidity. Annual temperatures range between 20 to 35 °C (68 to 95 °F). From June through September, the south-west monsoon brings in heavy rains, as Kottayam lies on the windward side of the Western Ghats. From October to December, Kottayam receives light rain from the northwest monsoon. The average annual rainfall is 3200 mm.
Kottayam is bordered by Pathanamthitta district on the south, Alappuzha district on the west, Ernakulam district on the north and Idukki district on the east
