This paper examined the onset and ending timing of each season based on the long-term (1920-1999) daily maximum, mean, and minimum temperatures as well as its impacts on the changes of flowering timing of the Forsythia, Azalea, and Pear at 6 weather stations in South Korea: Gangneung, Seoul, Incheon, Daegu, Jeonju, and Busan. Significantly, in the 1990s compared with in the 1920s, spring and summer started earlier by 16-23 days and 7-13 days respectively, while autumn finished later by 6-26 days. The shortened winter (22-49 days) as well as the earlier beginning of spring led to the earlier flowering of the Forsythia (6days), Azalea (8days), and Pear (4days) across South Korea.

Keywords: Climate change, Seasonality, Flowering timing, South Korea