The warm and windy conditions back on April 23 and 24 opened most of the lakes in Otter Tail and Becker counties. In extreme northern Minnesota the cold weather that followed those two days kept the ice on many lakes near the Canadian border until very recently. Lake of the Woods was not considered to be ice-free until May 8 and several lakes around Ely, Minnesota did not open completely until May 10 or 11. Most of the lakes in Minnesota became ice-free about ten days later than average. This is not surprising considering the cold winter and the cool spring that this region has experienced.
Phenology is the study of the timing of natural events and many residents in Minnesota will track the ice in and out days every year. For me, I keep track of when my ornamental crab apple trees flower each spring and they will be blooming very late this year.