According to the Intergovernmental Panel of Climate Change (IPCC), the forecast for the year 2100 is an increasing of global average temperature, whose impacts will produce real risks of coastal flooding and erosion due to climate changes. São Paulo State (Brazil) has around to 500 km coastline length. The main coastal and harbours impacts of this scenario were first studied in the physical model of Santos Bay and Estuarine Harbour, built in the Hydraulic Laboratory of São Paulo University in 2004, producing also a flooding map for this Central Coastline of São Paulo State. Study cases for the North and South Coastline are being evaluated according to the relative sea level scenarios. All the studies use local long tidal data series. The main purpose of this research was to get initial conceptual description about the impacts of relative sea-level rise on coasts and sea harbours to get adequate guidelines for Master Plan Municipalities Policies.