A simplistic theoretical model is presented and is used in an attempt to identify major variables affecting Lancaster Sound's clearing process in 1978, but some reference is made to other anomalous years (1963, 1970). The variables likely affecting Lancaster Sound's 1978 clearing date are: the predominance of easterly winds in July and August and calm in March; cooler than normal air temperatures which shortened the thaw season and thickened the ice cover; reduced sunshine levels resulting from above normal cloudiness; and above normal quantities of thick ice. Wind direction seems to be the most important variable. Westerly winds are associated with 75% of clearings. Clearing date distribution in Lancaster Sound was found to fit a normal distribution, the mean clearing date occurring in the first week of July. A 4% chance of clearing exists after September 1 and 16% after August 7.