Temporal patterns of water quality variation in Khlong U-Tapao river basin of Thailand were analyzed for 21stations along the river basin. This research objective is to study correlation of water quality by temporal variation of climatic-hydrology in years of 2007-2013. Using multivariate statistical analysis to analyze water quality of dataset 9 parameters such as pH, water temperature (WT), turbidity (TB), conductivity (CD), dissolved oxygen, (DO) biochemical oxygen demand (BOD), total coliform bacteria (TCB), fecal coliform bacteria (FCB) and Ammonia Nitrogen (NH3-N). The results show that seasonal change has affected to water quality by variation of climatic-hydrologic parameters. The climatic-hydrologic water quality relationship is maximum climatic temperature had positive with WT but negative with NH3-N. The temporal hydrologic-water quality relationship is precipitation had positive with TB but negative with WT, pH and DO. Water inflow had positive with TB but negative with WT and CD. Water outflow had positive with TB and DO but negative with WT. Water level had positive with TB, BOD and TCB. The spatial-temporal hydrologic-water quality relationship is river cross-section had positive with WT and CD but negative with DO. The assessment from multiple linear regression equations can explain water quality variations by climatic-hydrologic factors. Therefore, water quality management should be consideration climatic-hydrologic variation to provide basal information for developing improved water pollution control procedures of Khlong U-Tapao river basin.