This paper demonstrates the sensitivity of morphological process-based models to the chronology of input wave conditions. In this research the effect of an emerged offshore breakwater on the morphology of the beach is investigated. A 30 day long morphological simulation with real time history of the wave (brute force - base case) is compared with 150 different simulations of the same case with schematized wave conditions comprising different chronologies. The comparison between each case and the base case is quantified via the Brier Skill Score. This research shows that the skill score of a simulation largely affected by the sequence of the input wave conditions, and the best result is obtained by averaging all 150 simulations.