Passive microwave data from the Nimbus 5 and Nimbus 7 satellites have been used to determine baseline information on the interannual variability in monthly average sea ice distributions in the north polar region over the period 1973--1987. Monthly maps of the spatial range of ice distributions found for the 1973--1987 period show that, for instance, in February the greatest interannual variability occurs in the Sea of Okhotsk and in July particularly high interannual variability occurs in both Hudson Bay and the northern Barents Sea. In contrast, the portions of the ice edge with the least interannual variability in their February ice distributions lie in the southern Greenland Sea (59¿--67¿N) and immediately to the south and west of Svalbard. Plots of percent variability by month show that the marginal ice zones of the Sea of Okhotsk and the Bering Sea have their greatest ice distribution variability in winter and early spring, while the central Arctic has its greatest variability in late summer, and Hudson Bay has its greatest variability in July and November, during the ice decay and ice growth seasons, respectively. Since none of the regions showing high variability experienced a consistent (or even near-consistent) trend toward either increasing or decreasing ice coverage, the demonstrated variability cannot easily be attributed to climate change. The maps and analysis presented here provide a 1973--1987 baseline against which future northern hemisphere sea ice distributions can be compared in the continuing attempt to analyze global climate and to determine whether or not significant climate change is occurring.