A hydrodynamic investigation of the Patos Lagoon estuary serves as a fundamental framework for analyzing its inherent processes. This exploration facilitates a comprehensive comprehension of consequential events affecting the estuary, including river flow, prevailing winds, ambient and surface temperatures, salinity, and velocities. The present study analyses the hydrodynamic patterns in the Patos Lagoon estuary during the El Niño and La Niña events of 2015 and 2010, contrasted with the neutral conditions of 2013. Employing the three-dimensional TELEMAC-3D model within the Open TELEMAC-MASCARET numerical modeling system, the research concentrates on specific locales: the entrance of the Barra breakwaters and the urban core of Rio Grande municipality. Detailed analysis of time series data collected at varying depths within these sites enables a comparative evaluation of hydrodynamic trends across the three-year duration.