The most dominant mode in the EOF analysis of the seasonal June July August(JJA) rainfall anomalies over Thailand. The proportion of variability in first mode it accounts for 31% of the total variance. The left figure show eigenvector and In the right figure show principal component time series in JJA the first mode show that the relation of the eigenvectors is negative over the most area of Thailand. But it is positive over at the some area of the southern of Thailand. The values of standardized(PC’s), it was found that there was the most negative in 1954 found that It was high rainfall in the most area of Thailand. On the contrary, there was the most positive in 1994 found that, low rainfall in this area.