Sea Surface temperatures

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

Sea surface temperatures in early summer around western Alaska often show wide variation due to the season-to-season variations in the timing of sea ice melt, ocean currents, winds and discharge from rivers into the oceans.
An easy way to see just how much this varies is to compare the same dates in different years. This week's graphic compares the average sea surface temperatures for the week of June 7-13,2025 to the same week in 2024.
Most of southern Norton Sound and the Yukon Delta is cooler this year compared to last year. This is likely due to river water being discharged into the ocean that is cooler than last year due to the low late May and early June temperatures. However, in northern Norton Sound there are areas where ocean temperatures are higher than last year. This is likely related to the comparative warmth and earlier ice loss. The Bering Strait north into the southern Chukchi Sea shows warmer waters due to less sea ice. Ocean temperature comparisons around St. Lawrence are highly variable, with patches of both warmer and cooler water.
As we move into mid-summer, some of these variations will start to smooth out and storminess and sunshine will become especially important. As we experienced last summer, frequent storms keep the upper layers of the ocean well mixed, while excessively warm sea surface temperatures in early and mid-summer 2019 resulted in part from the warming effects of more sunshine and few storms.