Nares Strait is an important passage for the export of perennial sea ice from the Arctic Ocean to the North Atlantic Ocean. Normally, the southward flux of sea ice is obstructed between mid-February and mid-July when the ice in Nares Strait consolidates, often behind a stable ice arch that forms at its south end in Smith Sound. During the winters of 2007 and 2009 the ice in Nares Strait did not consolidate. These are the first recorded incidences of such an event in the Canadian Ice Service ice chart records (1968 to present) and the result was unprecedented ice conditions in the region. In 2007, greater than normal amounts of perennial ice were exported from the Arctic Ocean into Baffin Bay during the winter and spring months. In 2009, a persistent ice arch formed at the north end of the strait in the Lincoln Sea; the arch blocked the flow of perennial ice from the Arctic Ocean into Baffin Bay and allowed for the formation of a latent-heat polynya that extended the whole length of the strait during the winter and led to the early clearing of all the ice in the strait by May 2009. In this study we use the Canadian Ice Service Digital Archive of Regional (weekly) ice charts to examine historical normal and anomalous sea-ice consolidation patterns for Nares Strait. With a focus on 2007 and 2009, we then explore the factors important to: (1) the consolidation or nonconsolidation of sea ice in Nares Strait during the winter months; and (2) the formation of a permanent winter ice arch at the north end of Nares Strait. The factors investigated include air temperatures, winds, tides, ocean currents and ice pressures/shear strength. It is hoped that results from this study will assist with the development and validation of numerical models that resolve sea-ice dynamics in Nares Strait and also provide a useful starting point for the future downscaling of general circulation model results with a view towards improving future predictions of ice conditions in the region.