A simplified method to estimate blooming dates of Prunus yedoensis using “the number of days transformed to standard temperature (DTS)” is proposed. The method discussed in our previous papers required rather complicated procedures. For example, to obtain optimum starting dates and the mean DTS accumulations at each site, it was necessary to have relatively long records of daily mean temperature and actual blooming dates. By the simplified method, we only need daily mean temperature for the year under consideration. For DTS, the same value DTSm (21.5 days) are used for all stations in Japan. The value is determined by using data at 38 meteorological observatories. This simplified method was tested at 20 meteorological observatories which were not used to determine starting date (D*). The test showed increase in RMSE compared with the previous methods as expected. This seemed to be attributed to introduction of a constant DTSm to all stations instead of determining the value at each station. The method is applied to estimate blooming dates at parks in western Japan noted for the cherry blossoms. It is shown that accuracy of 2-3 days of RMSE are obtained to the parks where daily mean temperature data are available within 4-5km.
