Anomalous wintertime weather in the extratropical Northern Hemisphere is closely linked to the Northern Annular Mode (NAM), which is characterized by seesaw-like air pressure anomalies between the Arctic and midlatitude ocean basins. Despite its relevance to climate risk assessment in a warming world, future changes in interannual NAM variability remain to be elaborated. Using a large-ensemble atmospheric simulation dataset of over 10,000 model years, we show that the NAM in a warmer climate accompanies a stronger Aleutian Low anomaly. This change is partly attributable to a stronger influence of the El Niño–Southern Oscillation (ENSO), a leading mode of tropical Pacific climate variability. This finding suggests enhanced potential predictability of the NAM under global warming.