Annual γ-exposure around a nuclear site has been evaluated from short term plume-exposures with annual statistics of meteorological condition in which wind directions counted in a sector of 16 compass points are considered to be on the center of the sector. In this report, effects of wind direction frequency distribution in a sector itself on the γ-exposure are described. Correction coefficients to be applied to conventional calculation are obtained. Methods of calculation of plume-exposure and formula of frequency distribution in a sector are discussed.