The 8-year (1991--1998) Pathfinder sea surface temperature data have been applied here to produce the objectively derived seasonality of the oceanic thermal fronts in the northern South China Sea from 17 ¿N to 25 ¿N. Several fronts have been clearly distinguished, namely, Fujian and Guangdong Coastal Water, Pear River Estuary Coastal, Taiwan Bank, Kuroshio Intrusion, Hainan Island East Coast and Tonkin Gulf Coastal fronts. The frontal patterns in winter, spring and summer are quite similar, whereas individual fronts display different modes of seasonal variability due to different mechanisms favoring those fronts. ¿ 2001 American Geophysical Union