When was the last major ice cover recorded on Lake Ontario?

The last major ice cover recorded on Lake Ontario occurred during the winter of 1977-78. This event is significant because it marked one of the most substantial faltering of ice cover on the lake in recent history. The extensive ice cover during this winter affected transportation and local ecosystems, and it was a rare occurrence compared to the overall trends in icing on the Great Lakes. Major ice cover on Lake Ontario has generally become less common in recent decades due to climate variations and warming temperatures, making the winter of 1977-78 particularly notable in the historical context of the lake's conditions.