Sandbar and beach-face evolution on a sandy beach can change between winter and summer profiles due to different wave conditions. A study on a sandy beach with a lagoon found that during storm waves, sand was eroded from the inner surf zone and deposited in the outer surf zone, creating a sandbar. When swell waves followed, there was more sand exchange, leading to a prominent berm on the beach face. The dynamics of the berm were influenced by wave conditions and the beach's initial shape. Bed level changes during individual swashes could be significant, but overall changes were balanced between erosion and accretion. The local beach slope could vary instantly. This research will help improve models for predicting beach evolution under different conditions.