In the literature, there are many studies for determining wind power potential. However, in most of these studies, it is assumed that wind speed suits for Weibull distribution without examining. In this study, importance of examining whether wind data fits to Weibull distribution was shown and an application was carried out for wind data’s of Bilecik/Turkey. Maximum likelihood estimation (ML) was used for estimation of scale (c) and shape (k) parameters of two-parameter Weibull distributions and then seasonal wind data for Bilecik was examined fitting to two-parameter Weibull distribution. Result of examination was shown that only data of summer season was suitable for Weibull distribution in 0.05 level of significance. For other season’s data groups, it can be doubt if wind power potential is correct, because data groups don’t suit for Weibull distribution. Finally, it can be said that if researcher calculate wind power potential without examine the weibull fitting, results won’t be correct most possibly and these incorrect results may cause both power and cost losses.