The mountain of ice on Lake Superior was glacial blue in the distance, 16 Feb 2014. People provide some scale (photo by Kate St. John)

27 February 2025

This morning I am in Duluth, Minnesota where today’s temperature will range from 30°F to 39°F, far warmer than my last visit in February 2014 when it was –16°F to 0°F.

That was the winter of the Polar Vortex when it was so cold for so long that Lake Superior froze solid — a rare occurrence because it is so deep. When our birding group we reached the shore we saw big hills of ice and very few birds. So we got out of the van and climbed the lake.

Standing on Lake Superior’s ice while I take this photo of the mountain of ice in the distance, 16 Feb 2014 (photo by Kate St. John)

This week I won’t be climbing the lake because most of it is open water (shades of blue on the map) and the shoreline we visited northeast of Duluth is only partially frozen. In fact, as of last Saturday, total ice cover for all five lakes is only 38.5% (gray and black on the map).

Great Lakes ice cover 22 Feb 2025 from Great Lakes Environment Research Laboratory

Note that Lake Erie is more than 90% frozen because it’s so shallow.