🌊 Why can one Great Lake be nearly 80°F while another is still in the 30s? It all comes down to depth, water volume, latitude, and wind. While the sun warms the surface of every Great Lake in summer, shallower lakes like Erie heat up much faster because there’s less water to warm. In contrast, Lake Superior is the largest, deepest, and farthest north, so its enormous volume of cold water changes temperature much more slowly. On top of that, winds can trigger upwelling, bringing frigid deep wate