Nagaon is centrally located within the state of Assam, nestled in the fertile plains of the Brahmaputra Valley. The city itself is relatively flat and is famously divided into two distinct halves by the Kolong River, a tributary of the mighty Brahmaputra. The broader district is bounded by the Brahmaputra River and Sonitpur district to the north, and the Karbi Anglong and West Karbi Anglong districts to the south.
The geography is characterized by rich alluvial soils, deposited by the Brahmaputra and its tributaries over millennia. This makes the surrounding region incredibly fertile and ideal for agriculture. Beyond the city limits, the landscape transitions into swampy lowlands, small lakes (beels), and dense forests that gradually give way to the hills of Karbi Anglong.
The region shares the humid subtropical climate typical of Assam, experiencing heavy monsoonal rains that replenish its water bodies but also pose seasonal flood risks.