Flood early warning systems are recognized as one of the most effective flood risk management instruments when correctly embedded in comprehensive flood risk management strategies and policies. Many efforts around the world are being put in place to advance the components that determine the effectiveness of a flood early warning system. The aim of this research is to contribute to the understanding of the risk knowledge and forecasting components of flood early warning in the particular environment of tropical high mountains in developing cities. These represent a challenge taking into account the persistent lack of data, limited resources and often complex climatic, hydrologic and hydraulic conditions. The contributions of this research are intended to advance the knowledge required for design and operation of flood early warning in data-scarce watersheds from a hydrological perspective, without neglecting the crosscutting nature of flood early warning in the flood risk management process.