This paper examined seasonal and annual rainfall trends of the Mae Klong River Basin in Thailand. Monthly rainfall data of eight stations were used for the period 1971‒2015. The non-parametric Mann-Kendall test was used to detect trends whereas the slope of the trends was determined by Sen’s slope method. Datasets with significant serial correlation were corrected by the pre-whitening approach. For the dry season, 5 out of 8 stations showed increasing rainfall trends while for the wet season, 50% of the stations showed increasing trends. On an annual scale, 75% of the stations exhibited increasing rainfall trends. The upper region of the basin which contributes inflows to the Srinagarind and Vajiralongkorn Dams had increasing annual rainfall trends. For the entire basin, the trend analysis found increasing rainfall on both seasonal and annual scales. The results of this study can help water resource managers prepare better assessments and planning of water resources in the basin.
