Satellite data for Weather Index Insurance-AgricuLtural EaRly warning system (SatWIN-ALERT) For the more than 200 million farmers in Africa who depend on rain-fed agriculture, drought is a matter of life and death. Their vulnerability is often aggravated by a lack of access to risk management tools such as insurance, which also limits their ability to take productive risks on their farms. Index insurance, where compensation is based on weather or area yield metrics, rather than on measured losses, is an affordable alternative to traditional insurance. However, index insurance will only increase resilience to climate shocks if the index insured fairly reflects the risk for both farmers and insurers.   Index design processes are becoming increasingly sophisticated, utilizing multiple data-sources and models. A certain degree of basis risk (where compensation doesn't match observed losses) is, however, inevitable as insurance is not designed to target every risk. Anticipating basis risk that ensues from the complexity in the relationship between meteorological drought (rainfall deficit) and agricultural drought (soil moisture deficit) is a key challenge for the agricultural insurance sector.   We propose a new system, SatWIN-ALERT, which can be deployed in real time to detect and predict basis risk events as they happen. As such, it could unlock in-season actions (such as increased monitoring), or allow timely post-season index assessment or action, enabling aid agencies and governments to anticipate basis risk events, and take action to support farmers who are facing uncompensated agricultural losses. In effect, the facility to predict pay outs and losses bridges the gap between post hoc index insurance and forecast-based finance. SatWIN-ALERT provides a means of combining the data issued by existing platforms into integrated assessments of droughts and subsequent compensation. As such, it can be integrated into well-established and trusted insurance design systems, such as the ARC risk viewer (ARV) or the IRI Social Network for Index Insurance Design (SNIID).   SatWIN-ALERT builds on existing state-of-the-art practices to take a sophisticated approach to basis risk management, allowing index insurance to play an improved role within climate risk management and development. We also bring together novel existing participatory and meteorological research to build systems that are suitable for operational use in ODA countries. To do this, we draw on fundamental research on monitoring of environmental conditions, and on recent improvements in forecasts - especially on sub-seasonal to seasonal time scales, working with established partners to bring results to hundreds of thousands of farmers. We will focus on countries identified as important to our partners, specifically Malawi for our participatory research, plus Nigeria, Senegal, Malawi, Zambia and Ethiopia (amongst others) for our basis risk case studies.  In summary, the proposed project will develop a novel operational system (SatWIN-ALERT), which empowers farmers to benefit from robust financial instruments, based on state-of-the-art models, observations and forecasts. Partnership with leading practitioners in Africa will enable SatWIN-ALERT to sit within existing insurance systems to revolutionise basis risk management and build the resilience of millions of farmers to weather-related hazard. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.