Rainfall constitutes an essential component of the water cycle and is the prime source of groundwater recharge. In recent decades, groundwater exploitation has significantly increased, particularly for agricultural purposes, because large parts of the country have little access to rainfall due to frequent monsoon failures. In this context, an attempt is made to study the rainfall variability trend analysis. The study area selected for the research is the Vannathangarai watershed of the River Noyyal basin, the tributary of River Cauvery in South India. Rainfall data for 33 years were collected from 12 rain gauge stations in and around the watershed. The study explores the trends of rainfall, its variability, and the connection between rainfall intensity and the number of rain days. It is evident from the current analysis that October is the rainiest month, and the North-Western monsoon provides maximum rainfall. South West monsoon rains are highly variable than all other seasons. The western region receives the maximum rainfall than all other areas.