This dataset presents monthly-resolved Sr/Ca and δ13C of coral core TH3A from Ko Racha Yai (Siam Bay), Thailand, southern Andaman Sea. Core TH3A was drilled from a living Porites sp. coral in 2011. Coral skeletal material was microsampled at an average resolution of 17 samples per year and measured for Sr/Ca and δ13C at MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany. The measured values were then linearly interpolated to obtain monthly resolution records covering the time interval from March 1985 to July 2010. Coral skeletal Sr/Ca is a proxy for temperature and coral skeletal δ13C reflects various parameters, such as the availability of light for photosynthesis and changes in the autotrophy-heterotrophy balance. The proxy records provide insights into temperature changes and coral response to thermal stress in the southern Andaman Sea during the satellite era.