Flowering dates of Prunus yedoensis observed by the Meteorological Agency were investigated for changes of latitudes. Flowering dates of normal year at the sites among the regions from 31°N. L. to 35°N. L. at a leading part in the Pacific coast were hardly different from each other. At northern regions above 35°N. L, flowering dates did not advanced as gain for latitude. Flowering dates changed year by year. At northern regions of Japan, Flowering date in the mild winter were earlier than that in normal year. On the other hand, Flowering date in the mild winter were later than that in normal year at southern regions. Effects of the winter chilling on the release for dormancy of flower buds in Prunus yedoensis were-investigated. There were negative relationships between the numbers of chilling days and the daily mean temperature at flowering days. Dormancy was not released in the midwinter days whose daily mean temperatures were below 0°C.