Phenological properties of woody species were compared between two urban climates during 1997 and 1998. The study areas were Chungdam Park, Chungdam-dong, Kangnam-gu, Seoul (the urban center, 43 species) and Namhan-sansung Area, Sansung-ri, Joongbu-myon, Kwangju Gun, Kyonggi Province (the urban periphery, 16 species). Distance between these sites was 13.5 km. The differences of budding, foliation, and flowering times (1997 versus 1998) were 10.9, 3.2, and 7.4 days, respectively. Species that budded and flowered earlier were strongly influenced by Nuttonson’s Index (Tn) of February and March, but those with later dates were only weakly influenced. Unlike for budding and flowering times, foliation time was determined by air temperature or other factors in the leaf-growing season rather than by Tn. The Tn influence over phenology was stronger in shrubs and lianas than in trees. Phenophases in Chungdam Park appeared earlier than those in the Namhansansung area. The phenological differences between the two areas were 7.3 days in budding time, 8.3 days in foliation time, and 10.2 days in flowering time in mean values, with variations among species. Based on flowering-time data, the phenological variation between the two areas was equivalent to a 2.5° latitude difference. Budding time varied the most (20 days) inZelkova serrate, compared with only 3 days forPrunus padus. Differences in foliation time ranged from 15 days (inAlnus hirsute andStyrax obassia) to 0 days (P. padus). Flowering time differences were largest (24 days) inRhododendron mucronulatum and smallest (2 days) inP. padus. One can conclude that heat pollution in the urban center in Seoul severely changed phenology, and that sensitivity to that pollution differed among plant species.