This study investigates the effects of air‐sea interaction on the simulated East Asian summer monsoon (EASM) climate in a regional climate model. An ocean mixed layer model with a revised surface roughness length formulation that was originally designed for tropical cyclone simulation and a prognostic sea surface skin temperature scheme that considers the heat budget at the water surface are systematically evaluated on the monsoonal climate over East Asia for July 2006 in the regional Weather Research and Forecasting (WRF) model. Also, 9‐year (2000–2008) June–August simulations are performed to evaluate the overall impacts of these three components on the simulated EASM climatology. The 1 month simulation for July 2006 reveals that the inclusion of the ocean mixed layer model cools the water surface due to enhanced mixing, in particular, when winds are strong. Such cooling is largely compensated by the inclusion of prognostic skin temperature since solar heating in daytime overwhelms the cooling in nighttime. The revised surface roughness length effectively reduces the surface heat flux by reducing the exchange coefficients, against the conventional Charnock formula. Consideration of the three components together results in the reduction of systemic biases of excessive precipitation and weakening of the North Pacific high in the summer climate from 2000 to 2008. It is concluded that the methodology designed in this study can be an efficient way to represent the air‐sea interaction in regional atmospheric models for numerical weather prediction and climate simulation.