It may be spring now, but it certainly doesn’t look or feel that way for the Great Lakes, most of which are still ice-bound. Superior, Huron, and Erie are still almost entirely covered by ice, while Michigan is less than half covered. The only lake not ice-bound this winter has been Ontario at the far-right. Image from LANCE MODIS taken on March 16th.

You may be wondering why Lake Ontario is the exception to the frosty rule here. Ontario’s average depth is about 283 feet, only Superior has a greater average depth (Erie is the shallowest, so even though it’s further south than Ontario, it’s often the first to freeze). Furthermore, Ontario is located at a lower latitude than Superior and Huron, and it’s relatively smaller surface area maximizes its heat retention.