We observed sea clutter in the sea area east of the Daini Kaiho sea fort in Tokyo Bay using an X-band radar, and obtained data from 21,996 cells by 47 consecutive observations. In order to investigate the statistical properties, we performed estimation of parameters by maximum likelihood estimation and a test of goodness of fit by the Akaike Information Criterion (AIC), as models for the Weibull, log-Weibull, and log-Normal distributions. The reflected intensity distribution of sea clutter was found to obey the Weibull distribution better than any other distribution, and we therefore made a study using the shape parameter of the Weibull distribution. It was found that sea conditions such as swells and wind waves affect the statistical properties of sea clutter. (C) 2016 Wiley Periodicals, Inc.