First Alert Weather In-Depth: how this year’s ice coverage on Lake Ontario compares to the past

ROCHESTER, N.Y. – It’s always fascinating to track ice coverage across the Great Lakes each winter season. Even as we reach the early spring season, analysis shows that some ice remains on the eastern end of Lake Erie. And if you look closely, you will still find patches of ice clinging to parts of Lake Ontario, especially along bays and waterways near Watertown.

But how does this year compare to past winters? When isolating Lake Ontario, historical data reveals significant year-to-year variation. At its peak in 1986, nearly 45 percent of the lake was covered in ice. Even with a frigid February this year, the maximum ice coverage only reached about 25 percent. On the lower end of the spectrum, 1983 saw just 15 percent of total ice coverage.

One common question is whether Lake Ontario has ever completely frozen over. While some reports suggest it has, the truth is uncertain. The years often cited—1875, 1888, and 1912—predate satellite imagery, meaning we lack a definitive visual confirmation. However, firsthand accounts from those times describe people walking across the frozen lake to reach Toronto.

What is clear, however, is that ice coverage on the Great Lakes has been declining over the past 50 years (1973-2023). While ice levels fluctuate from year to year, long-term data reveals a steady decrease—by some estimates, total ice coverage has dropped by roughly 20 percent. This trend is not unique to the Great Lakes; many lakes across the Northern Hemisphere are freezing later in the season and thawing earlier in the spring.

While each winter brings its own variations, the broader pattern suggests that ice coverage is steadily diminishing—a change that will be important to monitor in the years ahead.