Abstract
High magnitude events, like Ex‐Tropical Cyclones, are likely to change in their trajectory, magnitude, and frequency under future climate change scenarios, and have the potential to significantly affect coastal landforms and erosion processes. We evaluate the incidence of Ex‐Tropical Cyclones on Māhia Peninsula, Aotearoa, New Zealand, and evaluate whether the occurrence and magnitude of these storms can explain observed retreat rates of the youngest Holocene marine terrace. By combining a simple empirical inundation model with backwearing rates measured from aerial imagery, we show that there has been a recent increase in terrace retreat (since 2015), where the landform elevation is low enough to be inundated. The most recent Ex‐Tropical Cyclone (Gabrielle in February 2023) swept sections of the shore platform free of debris and likely had an effect on local backwearing rates, but retreat rates varied considerably around Māhia Peninsula. The incidence of Ex‐Tropical Cyclones making landfall at Kahutara Point, however, is too infrequent to fully explain the observed retreat, especially for higher terrace risers that may be protected by back‐beaches and/or collapsed cover deposits. Retreat rates are temporally and spatially variable, and their vulnerability to extreme storms may cause an accelerating decay from post‐event weakening. Ex‐tropical cyclones can damage the integrity of marine terrace structures and contribute to erosion, but they are sometimes too infrequent to explain the longer term erosion rates of coastlines.