Attila Jaeger develops an application which notifies a vehicle’s driver of upcoming road weather dangers. This application maps the information evaluated by in-vehicle sensors in order to draw conclusions on the current weather condition. Comprehensive data basis is gained by sharing information with other vehicles using Car-to-X communication. In order to prove usability of the presented approaches, the developed application and selected concepts are implemented and deployed within the context of large scale Car-to-X field operational trials simTD and DRIVE C2X. Car-to-X communication is considered as the next major step towards a significant increase in road safety and traffic efficiency. Contents In-Vehicle Road Weather Hazard Detection Calculations with Rectangles Mobility Data Verification Driver Notification Strategies Reference Implementations Evaluation Results Target Groups Lecturers and Students of Informatics, especially in the Field of Application Development for Vehicular Ad-Hoc Networks and Distributed Weather Detection Practitioners Working in the same Field The Author Attila Jaeger completed his doctoral thesis at the Integrated Circuits and Systems Lab, Technische Universität Darmstadt, under the supervision of Prof. Dr.-Ing. Sorin A. Huss.