To study the isotopic composition of the Indian Summer Monsoon in Southern Oman, we collected precipitation samples over the entire monsoon season 2018. Weekly integral samples were gathered with six automatic precipitation collectors along an elevation gradient, from the Salalah coastal plain (sea level) to the Dhofar mountains (700 masl). The samples were analyzed for δ18O and δ2H by laser cavity ring-down spectroscopy (Picarro L2130-i). Further information can be found in Müller et al. (2026).