Empirical Orthogonal Function analysis can be extracted variance of monthly mean rainfall from a total of 80 stations throughout all areas of Thailand. The rainfall variability was extracted into a quite significant measured by the first four modes, which explains 79.77% of the total variance, with each mode contains 57.64%, 12.94%, 6.31% and 2.88%ofthe total variance respectively (Fig. 4). The principal component