Climate change is increasing acute heat events, intensifying health risks and straining healthcare systems. This study aims to support heat-related diagnoses prediction models for Germany by assigning ICD-10-GM codes to relevant conditions identified from the literature. Using the OHDSI mapping tool and clinical validation, 64 heat-related conditions were coded, enhancing data standardization. This approach facilitates reliable inclusion of diagnoses in association analyses and paves the way for improved resource allocation during heat events.