AbstractSurf zone incident wave energy flux is dissipated by wave breaking which through viscosity generates heat. This effect is not present in shelf heat budgets and has not previously been considered. Pier‐based observations of water temperature in 1–4 m depth, meteorology, and waves are used to test a surf zone heat budget, which closes on diurnal and longer time scales. Wave energy flux is the second most variable term with mean contribution one fourth of the mean short‐wave radiation. The heat budget residual has semidiurnal and higher‐frequency variability and net cooling. Cross‐shore advective heat flux driven by internal wave events, rip currents, and undertow contribute to this residual variability and net cooling. In locations with large waves, steeper beaches, or less solar radiation, the ratio of wave energy flux to short‐wave radiation may be >1.