Climate change is altering the natural equilibrium of the Amazon ecosystem, which is in turn deeply connected to the Earth’s biogeochemical cycles. Understanding this relationship aids optimal rainforests management in the future. Previous research has investigated the role of environmental variables and climatic drivers, neglecting the influence of forest height and age. This study uses remote sensing observations of precipitation, vapour-pressure deficit and canopy height along with model estimates of tree age and aboveground biomass to show that tall and old Amazonian trees are three times less sensitive to precipitation variability than younger and smaller forests. Canopy size is found to be equally important to mean precipitation in controlling the response to interannual climate variability. Our results align with those of in-situ experiments. These findings could help better predict the response of the Amazon forest to future droughts and water stress.