Climate Watch

By Rick Thoman Alaska Climate Specialist Alaska Center for Climate Assessment and Policy International Arctic Research Center/University of Alaska Fairbanks

Temperatures this time of year across western Alaska regularly vary dramatically from west to east, much more so than is typical in the late summer and autumn.

For example, last Friday (April 5), the high temperature at Wales was 15°F while the high at Unalakleet was 40°F. This is the result of different land cover and the impacts of snow cover and sea ice as the sun gets higher in the sky each day. The snow covered tundra and the sea ice continue to reflect much of the incoming solar heating back to outer space, while from Nome eastward in many Aprils, low elevations start to show significant bare ground, which is much more effective at absorbing the sun’s warmth. Additionally, the 300 miles that separate the eastern Norton Sound coast from the Bering Strait and St. Lawrence Island means that eastern parts of the region are that much farther removed from the still cold air typically found over northeast Asia.

The graphic shows the April daily average temperatures at five communities in western Alaska. All communities show substantial warming through the month, but you will also notice that the temperature rises more slowly in April at Gambell than at the mainland communities. Temperatures in April rise fastest at Unalakleet, where the average temperature goes above freezing at the end of the month, a level not reached at Shishmaref until the fourth week of May. Of course, this represents the 1991 to 2020 average and no individual month ever sees a slow but steady increase in temperatures day after day over the course of month. But this kind of analysis helps us put the weather we experience, and what family and friends across western Alaska report, into context.