The mean inter-annual precipitations on the great basins vary from 75 to 300 centimetres (2.46–9.84 ft), the entire upper Madeira basin receiving 170.5 centimetres (5.59 ft).
Wastani wa mvua kati ya mwaka kwenye mabonde makubwa hutofautiana kutoka sentimeta 75 hadi 300 (futi 2.46–9.84), bonde lote la juu la Madeira likipokea sentimeta 170.5 (futi 5.59).