Rapid Arctic warming and decline in sea ice have been observed in recent decades. These trends will likely continue, potentially changing winter extremes elsewhere in the Northern Hemisphere. We use coordinated Polar Amplification Model Intercomparison Project (PAMIP) experiments to decompose the Northern Hemisphere winter cold temperature responses to future Arctic sea-ice loss and sea surface temperature (SST) change, separately, at 2C global mean warming. Cold extremes (20-year return period) will generally become warmer at high- and mid-latitudes due to Arctic sea-ice loss, with the largest warming in East Canada. SST change will warm cold extremes everywhere, overwhelming simulated sea ice-induced cooling responses in, e.g., southwestern United States. In general, the SST-induced changes dominate over sea ice-induced changes, with exceptions in East Canada, Nunavut (Canada) and North Pacific Russia. Our results suggest that if climate models do not adequately capture the sea-ice and SST components, cold extremes will be biased.