Cities are particularly vulnerable to rainfall-generated floods that are typically characterised by their rapid onset and localised nature. This implies that precipitation and catchment information need to be available at high resolution to reliably predict hydrological response and potential flooding. On the contrary, urban areas constitute a major knowledge gap as most flood risk studies have concentrated on natural basins and records of rain gauges and water level gauges in cities are scarce. While increase in intense precipitation as a result of climate change is expected in many areas around the world, it is at present not possible to assess how this will affect urban pluvial flood risk. Collection of reliable, high resolution data in cities needs to start urgently to build up datasets in support of urban flood risk assessment and to enable detection of changes in flood risk whether these are induced by climate change, urbanisation or other future developments. This study shows how implementation of polarimetric X-band radar can contribute to filling the knowledge gap of flood risk quantification in cities.