HARMONIZE collates existing multi-source climate, environmental, socioeconomic and health data, and collects new longitudinal data using drone technology and low-cost weather sensors, to calibrate and downscale Earth Observation, climate reanalysis and seasonal forecast datasets in areas most relevant for disease transmission. The main goal of the project is to develop cost-effective and reproducible digital tools for decision-makers in climate change hotspots in Latin America & the Caribbean, including cities, small islands, highlands, and the Amazon rainforest. HARMONIZE will collate existing multi-source climate, environmental, socio-economic and health data, and collect new longitudinal ground-truth data using drone technology and low-cost weather sensors, to calibrate and downscale coarser-resolution Earth Observation, climate reanalysis and forecast datasets in areas most relevant for disease transmission. The HARMONIZE digital toolkits will allow local researchers and users, including national disease control programs, to link, interrogate and use multi-scale spatiotemporal data, to understand the links between environmental change and infectious disease risk in their local context, and to build robust early warning and response systems in low-resource settings.