Given variable loading conditions and the occurrence of extreme flood events, marked by various periods of inundation and elevated water levels, a realistic, time-dependent evaluation of levee stability is crucial, particularly within the context of climate change. This paper fulfils this requirement by introducing probabilistic reliability analyses that incorporate transient input parameters. The derived failure probabilities are subsequently contrasted with conventional, steady-state design assumptions, by using a section of the Rhine dikes in Elchesheim-Illingen as a case study.