Abstract: The seasonal variation of the relationship between the cloudness and sea-surface temperature (SST) is examined by using of the simultaneous correlations. It is indicated that the correlations vary both with seasons and regions. In the central equatorial Pacific the positive correlation predominates throughout the year. The negative correlation is observed over the California cold current for whole year. In other regions a half-year alternation between positive and negative correlation is appeared.It is proposed that the positive correlation indicates the prominent role of SST in the interaction between the atmosphere and oceans, and the negative correlation shows the active role of cloudness. Finally, the great lag-correlation between the cloudness and SST may be linked with the large persistence of SST.