This work describes the extreme event of landslides occurred in January 2011 in the Rio de Janeiro mountainous region and discusses its relationship to the spatial and temporal variation of critical and prior rainfall. Interviews in the field let us establish the landslide initiation timing around the automatic pluviometer stations which supply detailed data on the rainfall intensity. The study concludes that the accumulated rainfall during the last months associated with high rainfall levels over 24 hours, along with local conditions like the direct impact of lightning and tremors 

resulting from landslides, formed the relevant conditions for thousands of landslides.