A ‘single point’ coupled ocean-atmosphere model is formulated to study seasonal temperature cycles with particular application to shelf seas. The simplified atmospheric module is consistent with the physical processes described by Gill [4] while the vertical exchange of heat in the ocean module is determined via a turbulence closure model. The various empirical coefficients in the atmospheric module were determined by fitting the model output to North Atlantic observational data over the latitude range 0° to 65° N. The model is then applied to the shallow, strongly tidal North Sea. The general validity of the model is demonstrated, thereby indicating that the seasonal cycles of the sea surface, T s , and ambient air, T a , are generally governed by a localised equilibrium. In shallow water (< 200 m) the amplitude of this seasonal cycle is modulated by both the water depth and tidal current amplitude. North Sea observational data confirm these model indications that large tidal currents decrease seasonal amplitudes. This study provides, for the first time, a quantitative estimate of this influence of shallow seas on adjacent coastal climates. It is shown how the model results can be sensibly approximated by generalised expressions - illustrating that mean values of both T s and T a vary with the cosine of latitude (up to 65° N) while their seasonal amplitudes vary directly with latitude and inversely with an exponent of water depth. Thus these generalised expressions can be conveniently used to provide boundary conditions in generalised ecological models. The model can also be used for (small amplitude) sensitivity analyses to examine, for example, the effect of changes in storminess or cloud cover.