Correlations between winter/summer temperature in Shanghai and SST in the Pacific areas and their interdecadal variations from 1873 to 2001s have been analyzed in this paper.The results indicate that temperature’s interdecadal variations exhibited obvious change in phase and an overall warming trend,and the correlations between Shanghai’s temperature and SST in the Pacific areas were significantly different on different time scales and in different areas.The correlation differences on different time scales possibly lead to uncertainties and inaccuracy in the statistical forecasting of short-range climate,using the sea surface temperature in the Pacific ocean as a predictor.The uncertainties can be reduced if the correlation differences on different time scales are considered in statistical forecasting.