Abstract: According to the sea surface temperature (SST) data observed by mooring buoys, we found subtidal variability signals in a period of 5-8 days off Dongshan Island in summer of 2016 and 2017, and the maximum amplitude was respectively 3.05 ℃ and 2.13 ℃. Combining with data of remote sensing SST, wind, OA Flux, and methodology of wavelet analysis, cross wavelet analysis, the analyse results that the subtidal variability signal in SST is respectively derived from shortwave radiation and coastal wind stress in summers of 2016 and 2017. The SST variation lags shortwave radiation for 1 day, and lags coastal wind stress for 2 days. Further study shows that the subtidal variability signals in 2016 and 2017 were both related to typhoons. The reason for different signal source was the intense coastal wind relaxation phenomena caused by typhoon in 2017 and it generated subtidal variability signal in coastal wind which influences the upwelling and SST. When the coastal wind relaxation phenomena was very weak in 2016, there was no subtidal variability signal in coastal wind. The mechanism of subtidal variability signal in SST in 2016 derived from shortwave radiation may be related to the change of local weather system caused by typhoon.