抄録
At any station, the yearly variation of the last frost day is not always in a close correlation with the average minimum air temperature in the spring of each year (Fig. 1). Climatologically speaking, however, it is clear that the lower the climatic minimum air temperature in the spring, the later the last frost day tends to appear. This relation is shown in Fig. 2 based on the data at 121 stations in Japan. The stations with large deviation on the graph (Fig. 2) are seen in basins (+), islands (-), mountain-tops (-) or coastal areas (-).
