This dataset comprises gridded precipitation fields, simulated hourly discharge values and simulated inundation areas and depths in the Ahr catchment in Germany for the reference scenario of the July 2021 flood and 25 spatial counterfactuals. The precipitation dataset contains the observed gridded E-OBS precipitation field and 25 counterfactuals shifted by one cell. Subsequently, the reference scenario and spatial counterfactuals are used as atmospheric forcing for the mesoscale hydrological model mHM set up and calibrated for the Ahr catchment, Germany. The model simulates hourly discharge series at seven gauge locations (Müsch, Kirmutscheid, Niederadenau, Denn, Kreuzberg, Altenahr, Bad Bodendorf) from which the event peak flows and flood event volumes can be derived. These discharge data is used as boundary condition for the RIM2D hydrodynamic inundation model which simulates inundation areas and maximum inundation depths along the Ahr valley between Müsch and Sinzig for the reference scenario and spatial counterfactuals.