Madagascar is increasingly vulnerable to extreme heat, which previous studies in multiple locations have linked to higher rates of diarrheal diseases. Elevated temperatures accelerate pathogen growth, degrade water quality, and strain sanitation systems, leading to increased risk of diarrhea outbreaks. This project investigates the national- and regional-scale causal relationship between heat exposure and diarrhea in Madagascar. We control for key confounders such as access to clean water and sanitation, and integrate satellite data estimates of temperature, humidity, and precipitation. By combining remote sensing, local health data, and spatial datasets on local population and socioeconomic conditions, this project informs targeted public health interventions in Madagascar and supports broader global efforts to mitigate climate-related health risks in low- and middle-income populations.