Intraseasonal variability of SST in the SCS is examined. The results demonstrate that characteristics of intraseasonal SST variations in summer are remarkably different from those in winter. In summer, the spatial correlation pattern of intraseasonal SST perturbations is zonally distributed in the monsoon region. They are characterized by the northeastward propagation. In contrast, it appears to be localized in the SCS region without any propagating signal in winter. In addition, intraseasonal SST fluctuations are highly related to zonal winds and Outgoing Long-wave Radiation (OLR) in summer. However, they are primarily associated with meridional winds in winter. It has potentially important implication that the monsoonal air-sea interaction in summer is somewhat different from that in winter.