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Abstract The El Niño Southern Oscillation and Pacific Decadal Oscillation (PDO) are key drivers of cool‐season precipitation variability in the western United States (US), including the Rocky Mountains. Together, they help modulate the north‐south “precipitation dipole,” a regional climate pattern operating on multi‐decadal timescales leading to dry conditions north of 40°N latitude when the south is wet, and vice versa. We investigate the natural evolution of this climate pattern using two precisely‐dated (5900 years ago to present), multi‐proxy, coeval stalagmite records of hydroclimate from Titan Cave, Wyoming, located just north of the modern‐day dipole transition zone. Consistent trace element and stable isotope records from the two stalagmites reflect the amount and seasonality of regional precipitation, documenting decreased winter snowfall and dry conditions over multi‐decadal intervals characterized by the warm phase of the PDO and more frequent and stronger El Niño events. 

Abstract High‐resolution records from past interglacial climates help constrain future responses to global warming, yet are rare. Here, we produce seasonally resolved climate records from subarctic‐Canada using micron‐scale measurements of oxygen isotopes (δ¹⁸O) in speleothems with apparent annual growth bands from three interglacial periods—Marine Isotope Stages (MIS) 11, 9, and 5e. We find 3‰ lower δ¹⁸O values during MIS 11 than MIS 5e, despite MIS 11 likely being warmer. We explore controls on high‐latitude speleothem δ¹⁸O and suggest low MIS 11 δ¹⁸O values reflect greater contribution of cold‐season precipitation to dripwater from longer annual ground thaw durations. Other potential influences include changes in precipitation source and/or increased fraction of cold‐season precipitation from diminished sea ice in MIS 11. Our study highlights the potential for high‐latitude speleothems to yield detailed isotopic records of Northern Hemisphere interglacial climates beyond the reach of Greenland ice cores and offers a framework for interpreting them.