The dataset includes speleothem oxygen isotopes used to reconstruct climate in southeastern Alaska during the past ~13.5 ka. In total, four speleothems were used in this reconstruction. Speleothems EC-17-7-A and EC-16-5-F were collected in July 2022 and May 2016, respectively, from El Capitan Cave (56.170 N, -133.320 E; 80 m.a.s.l). Speleothem WB-21-5-A was collected in Wishbone Cave (55.774 N, -133.191 E; 420 m.a.s.l.) and speleothem WA-21-6-A was collected in Walkabout Cave (55.776° N, 133.195° W; 350 m.a.s.l.) in May and June 2022, respectfully. The data collection was completed between 2016 and 2022. stable isotopes were measured on a ThermoFisher Delta V isotope ratio mass spectrometer.