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 reached the shore we saw big hills of ice and very few birds. So we got out of the van and climbed the lake.

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

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