With the large extent of open water along the coast even in midwinter, the temperature rarely drops down to more than 50°F. below zero, much higher than extreme winter temperatures in Siberia or Canada. Even with an extensive ice-lay the temperature is modified by the water, through crevices and open pools, though if the ice be deeply and generally covered by heavy snow the temperature is lowered. The highest summer temperature is 55° to 60° above zero Fahrenheit. Along some of the high cliffs the temperature is raised adiabatically when the air drops down from the ice-cap, so that in certain favorable localities the temperature never falls below 40° below zero Fahrenheit.
The temperature rises high enough about mid-June to melt the ice and snow; melting ceases about mid-August. By mid-September the sea-ice begins to form permanently in the fjords and deeper bays. The bays and fjords are generally occupied throughout the summer by drifting fields of ice; rarely are they free of icebergs.
Snow falls in every month of the year, but the first snows of summer that do not melt are those of late August or early September. The depth of snow, even after a winter's accumulation, is rarely over 2 or 3 ft., because the relative humidity is frequently so low that a great deal of snow evaporates even in the coldest weather. When the snow begins melting in June under the continuous sunlight, every canyon and valley holds a roaring torrential mountain stream which flows with heavy volume until melting ceases. Rain rarely falls; yet when the chinook comes down off the ice-cap, rain may fall even in January. The region is one of general low humidity.
The winds are cyclonic in character. The heaviest storms come from the southwest with destructive on-shore winds. In the bays and fjords the winds invariably blow down to the sea from the ice-cap, no matter what the wind may be above the plateau. Sudden winds sometimes sweep down off the plateau or from the ice-cap and drive the shore-ice out to sea even in mid-winter.
The period of continuous night begins about mid-October and ends about mid-February. Continuous sunlight begins about mid-April and lasts until mid-August. Between mid-February and mid-April the days lengthen and the nights shorten; between mid-August and mid-October the days shorten and the nights lengthen. The night is rarely so dark as to stop traveling or sledging entirely, and throughout the moon-lighted periods during which the moonlight is continuous, all activities can be carried on without difficulty. During the period of continuous sunshine, noon and midnight do not differ greatly in temperature or intensity of light. The air is always fresh and clean.