New local and semi-global tuning methods for a 3D site-specific propagation path loss model based on the uniform theory of diffraction are proposed in this paper. The purpose of the tuning methods is to efficiently incorporate measured data in the prediction process to enhance the accuracy of the path loss model in microcell environments. The performance of the proposed tuning procedures is compared with a third method that corresponds to a global tuning approach based on the least squares error technique. Our results show that the local tuning procedure outperforms any of the other tuning methods, by providing a significant reduction of the mean absolute error, up to 35 % in error reduction was observed.