Kumbakonam is located at 10.97°N 79.42°E. It is situated 273 km (170 mi) south of Chennai, 96 km (60 mi) east of Tiruchirappalli, and about 40 km (25 mi) north-east of Thanjavur. It lies in the region called the “Old delta” which comprises the north-western taluks of Thanjavur district that have been naturally irrigated by the waters of the Cauvery and its tributaries for centuries in contrast to the “New Delta” comprising the southern taluks that were brought under irrigation by the construction of the Grand Anicut canal and the Vadavar canal in 1934. It has an average elevation of 26 metres (85 ft). The town is bounded by two rivers, the Cauvery River on the north and Arasalar River on the south.
Although the Cauvery delta is usually hot, the climate of Kumbakonam and other surrounding towns is generally healthy and moderate. Kumbakonam is cooler than Chennai, the capital of Tamil Nadu. The maximum temperature in summer is about 40 °C (104 °F) while the minimum temperature is about 20 °C (68 °F). Kumbakonam receives an annual rainfall of 114.78 cm (45.19 in) every year. The region is covered with mainly alluvial or black soil which is conducive for rice cultivation. Other crops grown in Kumbakonam include mulberry, cereals and sugarcane.
The town of Kumbakonam is surrounded by extensive paddy fields. Methods of irrigation were considerably improved following the opening of the Mettur Dam in 1934. The fauna of the Cauvery Delta is limited to cattle and goats. The town is situated at the western flank of the Kumbakonam-Shiyali ridge which runs along the Kollidam river basin separating the Ariyalur-Puducherry depression from the Nagapattinam depression. This granular ridge projects further eastwards penetrating the Puducherry depression and forms a hard layer of cretaceous rock underneath the sedimentary top soil.