In recent years, significant experience of the effects of high wind and flooding on nuclear installations has been gained worldwide. These phenomena may simultaneously affect all the structures, systems and components important to safety at a nuclear installation site. By detailing the methodologies and providing case studies for the evaluation of meteorological and hydrological hazards, this publication supports IAEA Safety Standards Series No. SSG-18, Meteorological and Hydrological Hazards in Site Evaluation for Nuclear Installations. In the first part of the publication, wind hazards relating to tropical cyclones, tornadoes, extratropical storms, thunderstorms and wind-borne debris are discussed. The second part covers external flooding hazards (excluding tsunamis) relating to wind induced coastal flooding, wind generated waves on rivers, extreme precipitation and runoff events and the sudden release of impounded water.