The High-Impact Weather Assessment Toolkit (HIWAT) is a SERVIR-supported early warning forecasting system for extreme weather developed by the SERVIR hub in South Asia, in collaboration with NASA scientists and local partners. Using NASA satellite data and advanced computer models, HIWAT provides up to 54 hours of advance notice for hazards such as heavy rainfall, flash floods, lightning, hailstorms, tornadoes, and forest fires—helping authorities reduce disaster risks and protect lives and property. Integrated into forecasts and early warning systems in Nepal and Bhutan, HIWAT has also been tailored to the Bangladesh context, where the national hydrometeorological department operates the system independently on its own high-performance computing infrastructure. In Nepal, HIWAT supported early warning and action ahead of the September 2024 monsoon floods, and its forecasts also power the Prakop mobile app, which allowed teachers in Benighat Municipality to warn students and residents two days before flooding. In response to user needs, SERVIR expanded HIWAT to include a two-day forest fire outlook for Nepal’s national Forest Fire Detection and Monitoring System to support earlier action, better resource deployment, and proactive fire prevention.