14 July 2021
In summer, folks in western Pennsylvania and northern Ohio flock to Lake Erie‘s shore to beat the heat. The water provides a respite but in July the western end is hotter than anywhere else in the Great Lakes. That’s because Lake Erie is shallow and shallow water is quick to take on the temperature of the surrounding air. So how shallow is Lake Erie?
Lake Erie is the fourth in line of the five Great Lakes and happens to be fourth largest by surface area — 9,940 square miles.
But as you can see in this bathymetric map it is also the shallowest (blue is deep, red is shallow). Lake Erie’s average depth is only 62 feet with the deepest spot just 210 feet near Long Point, Ontario.
It’s easier to see how shallow it is in this diagram from Michigan Sea Grant. Even Lake Ontario, the smallest by surface area, is 3.8 times deeper! (Lakes Michigan and Huron are superimposed on each other because they have the same pool level, 577 feet above sea level. Click here to see the complete diagram.)
Since the shallowest water is first to heat and first to freeze, the surface temperatures roughly match the lake depths. As of yesterday, 13 July 2021, the water at the western end of Lake Erie was close to 80 degrees F.
The lake is warm because it is so shallow. See the current temperature map here.
(photo and first two maps from Wikimedia Commons, Great Lakes system profile from Michigan Sea Grant, Great Lakes Suface Temperature from NOAA; click on the captions to see the originals)