Abstract Sea surface temperature (SST) and salinity (SSS) variability in the Red Sea influences marine ecosystems, hydrologic variability, and circulation within and outside of the Red Sea. However, understanding of multidecadal surface variability in the Red Sea is limited by short and sparse observational records. To extend beyond the limited observational period, we present 346 years of paired records of Sr/Ca and δ18O from a central Red Sea Porites sp. coral providing centuries‐long, sub‐annually resolved records of SST and relative SSS (δ18Osw) variability. We synthesize our records with published northern Red Sea coral records to investigate basin‐scale patterns. Both sites exhibit coherent multidecadal SST and δ18Osw variability, which are anticorrelated to the Atlantic Multidecadal Variability and document the crucial role of Indian Ocean inflow in modulating Red Sea surface conditions. Our results refine our understanding of multidecadal drivers of Red Sea surface conditions, with implications for regional hydrology, circulation, and ecology.