Abstract To describe the random movement of ocean wave exactly, the random field theory for local average sampling is introduced. In this work, the rotated empirical orthogonal function analysis (REOF) is proposed to estimate the significant wave height (SWH) from the data captured with marine X-band radar. After obtaining the rotated principal components (PC) of the radar image sequences, the standard deviation of the rotated PC is a new means of estimating SWH. The results show the advanced algorithm has a good correlation between the SWH retrieved by radar and that of the measured with the buoy. The root mean squared error (RMSE) of the SWH between the advanced model and the buoy is only 0.1440 m, which decreased about 22% compared with the EOF analysis.