The purpose of this paper is to depict the detailed distribution of surface wind over central Japan in consideration of the pressure patterns in the winter seasons. The distribution of surface wind on a local scale is affected not only by the flow pattern of the synoptic scale, but by local circulation, such as land and sea breezes, as a result of diurnal variations in the local pressure pattern. Generally speaking, as the latter is superimposed on the former, the wind distribution is more complicated on a local scale. In the winter season, however, a severe winter monsoon prevails over Japan and adjacent areas, while the local circulation is relatively weak, then the detailed distribution of surface wind is mainly influenced by flow patterns resulting from the winter monsoon. Invasions of the sea breeze are restricted to within a zone of approximately 15 kilometers from sea-coast and the alternation from land breeze to sea breeze occurs after 10 a. m., as shown in Fig. 3, in the area of Pacific sea-coast where the sea breeze is established during this season. Available data to reveal the detailed distribution of surface winds at optional times are so sparse that the data of climatological stations, where observations are made at 9 a. m. only, were mainly used in this study. First of all, one hundred sheets of daily maps of stream-lines of surface winds were drawn, using the data of 623 stations in this region. These maps show that the characteristic distribution of local wind systems is apparently perceived in relation to a gradient flow pattern, which is decided from synoptic weather maps at that time. Then the gradient flow pattern over central Japan, corresponding to the distribution of surface wind systems, was classified into 6 types as follows. Type I Gradient wind over this area exceeds 10m/sec and comes from 250° to 330°. (Wind direction represents angle measured clockwise from north.) Type II Gradient wind speed is the same as Type I. Gradient wind direction is included in the fanshaped domain from 330° to 20°. Curvature of isobars is cyclonic. Type III Same as Type II, but curvature of isobars is anticyclonic. Type IV Gradient wind speed is the same as the above, but its direction is between 30° and 60°. Type H Winter monsoon weakens and gradient wind speed lies below 10m/sec. Type FL Trough accompanied with cyclone and front affects the wind distribution on this area. The frequency of flow patterns is listed on Table 1.As shown in Table 2, transition of flow patterns prevails in the following order. (1) I—II—III—H—FL (2) IV—(III)—(H)—FLCase (1) is an ordinary cycle of the seouence of pressure patterns in winter season. As soon as a major through passes over Japan, a severe winter monsoon breaks out in this area and the flow pattern shows Type I or II. On the other hand, case (2) appears when the Siberian High moves to the northeastern part of Shiberian Continent. In the case of Type H and FL, the wind distribution is too intricate to deal with in this paper. Briefly speaking, in Type H a gentle pressure gradient leads to an unsystematic distribution of local wind, while in Type FL, the wind distribution is extremely different in each case. These two types are excluded from thie paper. Data of wind for the remaining types were arranged into the windrose, related to each of the flow patterns, for each of the meteorological stations. Fig. 5 illustrates an example of regional characterisitics of the windrose for Type IV in the Kanto plain. The prevailing wind direction is evident for most stations, though in certain parts of this area the prevailing frequency is absent and indistinct, where either a convergence line is formed between local wind systems or topography influences the wind direction in mountainous areas.