Galvanic corrosion can cause significant damage on aerospace structures due to mixed material components and aggressive operating environments under atmospheric conditions. Predicting both the galvanic corrosion magnitude and distribution is important to help inform the design and maintenance of new and existing structures, respectively. Prior efforts have developed atmospheric models for risk mapping, but validation has been in the form of simulated atmospheric environments in the lab, rather than actual corrosion processes in outdoor environments, with the latter being more representative of operational conditions for aerospace components. Therefore, the present work investigates the development and validation of an atmospheric model predicting the galvanic corrosion magnitude and distribution that is expected to occur in outdoor conditions.