This study investigates a vertical plate fin cooled by an oncoming turbulent flow. The base temperature of the fin varies periodically and the local heat transfer coefficient of the fin surface is determined by a conjugate convection-conduction analysis rather than arbitrarily specified. The heat conduction problem within the fin coupled with the boundary layer flow problem outside the fin surface are solved simultaneously. The calculated results include the effects of the conjugate convection-conduction parameter Nc as well as the oscillation amplitude and frequency of the base temperature on the fin cooling behavior.