Tropical South America’s hydroclimate is influenced by ocean-atmospheric oscillations. The physical mechanisms that teleconnect the Atlantic modes of variability with the evaporation, soil moisture and streamflow of the region remain unclear. This study uses composites of reanalysis, satellite and gauge data to identify the processes linking land-surface anomalies and ocean modes. It shows that the Atlantic Meridional Mode (AMM) generates cross-equatorial wind anomalies that affect moisture convergence, in turn modifying cloud cover, precipitation, radiation availability and hence evaporation. Evaporation anomalies are water- or energy-driven depending on the phase of the mode; streamflow anomalies follow those of rainfall. The spatial pattern of the impact of the AMM depends on the season analysed. The Atlantic El Niño (Atl3) affects the Guianas and eastern Orinoco because of pressure and trade wind strength variability. Therefore, these ocean-atmospheric modes impact the water and energy cycles and might influence regional climate extremes (e.g. droughts and floods).