
Great Lakes see a more than 500 per cent increase in ice coverage
Frigid air parked over the region caused a dramatic increase in ice coverage on the Great Lakes this week
There’s a glimmer of hope on the horizon for folks who live across Ontario's traditional snowbelts. Frigid temperatures enveloping the Great Lakes have led to a dramatic increase in surface ice coverage in recent days.
Ice coverage is critical to shutting down the process that creates lake-effect snow. While we have a long way to go before reaching that important milestone, the recent increase in lake ice is a positive step forward.
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The Great Lakes were historically warm to end 2024, and winter’s deep chill took its sweet time pushing into the region.
We had plenty of air cold enough to trigger formidable bouts of lake-effect snow across southern Ontario, but the lakes were so warm that it didn’t translate into ice coverage.
The lakes began 2025 with a basin-wide ice coverage of just 1.24 per cent.

A burst of cold weather to start the new year helped dramatically increase that number. NOAA reported on Friday, Jan. 10, that 10.93 per cent of the lakes were covered by ice.
Nearly one-quarter of Lake Erie was covered by ice to start the second weekend of January, accounting for most of the ice observed across the basin. Lake Huron was a close second, with just more than 17 per cent of the lake hosting some ice coverage.
Since data collection began in 1973, the average extent of ice coverage across the entire Great Lakes basin on Jan. 11 is about 17 per cent. That number would normally increase to a peak between 40 and 45 per cent coverage across the basin by the middle of February.

Consistently cold temperatures are needed for surface ice to build across the basin.
Shallower lakes are the first to freeze over––including Erie and Huron––while the larger and deeper lakes hold onto their heat deeper into the winter.
Record-warm temperatures across the region in 2024 helped keep Great Lakes ice to a minimum last winter.
Data collected by NOAA indicate that the region’s maximum ice coverage in 2024 reached just 16 per cent on Jan. 22. That was the lowest extent recorded in more than a decade.