Data from six sea level sites on the Canterbury coast, New Zealand, were analysed for short period (1–4 h) waves. Persistent waves with periods of 3.4 h in Pegasus Bay and 2.4 h in the Canterbury Bight were found. Their amplitude and phase are highly variable. Edge waves of similar period were found in simulations using a 2‐dimensional, harmonic, shallow water, numerical model. Numerical and analytical modelling showed that th...