Riada de Bilbao de 1983 Historical milestone · Bilbao, Bilbo Handia / Gran Bilbao, Bizkaia Image of Bilbao, not of the place itself. On 23 August 1983 a cold-drop storm dropped 252.6 l/m² on Bilbao and caused the estuary to overflow, with severe flooding in the town center and much of the metropolitan area. 23 de agosto de 1983 Photo: _ion from Donostia, Euskal Herria (CC BY 2.0) What to see and do in Bilbao