This is a summary of the Technical Deep Dive (TDD) on Hydromet Services for Early Warning, held on September 12–15, 2016, in Tokyo. The event, which brought together more than 40 officials from 11 developing countries, along with World Bank project teams and key experts from Japan and Australia, allowed developing country clients to learn from Japan’s approach to hydrological and meteorological (hydromet) hazards, specifically its ability to translate modern and sustainable weather, climate, and hydrological services into national hazard and climate risk management strategies.