Great Lakes Water Levels Shift Amid Unusual Weather Patterns

Despite record-high precipitation, the Great Lakes water levels are below long-term averages for January on several lakes, prompting close monitoring.

Warmer Weather and Heavy Rain Dominate the Basin

The Great Lakes Basin experienced a week of unusually warm temperatures, up to 20°F above average, before colder air returned with the new year. Over two inches of precipitation drenched central and southern regions, contributing to elevated Great Lakes water levels in some lakes but failing to offset declines in others. Temperatures are forecast to remain below average, with lake-effect snow expected along the eastern shores.

Great Lakes Water Levels Reflect Mixed Trends

The Army Corps of Engineers reported that on January 3, water levels for Lakes Superior and Michigan-Huron were 2 inches lower than last month. Meanwhile, Lakes St. Clair, Erie, and Ontario are up by 7, 3, and 3 inches, respectively, over the same period. Year-over-year comparisons show declines ranging from 2 to 8 inches on all five lakes.

Compared to long-term January averages:

Superior, Michigan, and Ontario are 4 inches below normal.
St. Clair and Erie are 9 and 6 inches above normal.

The predicted changes for February 2025 include a 2-inch drop for Lake Superior, a 1-inch decrease for Lake Michigan-Huron, and a 4-inch decline for Lake St. Clair. Lake Erie is expected to remain stable, while Lake Ontario may rise by 1 inch.

Long-Term Data Highlights Variability

Water levels continue to fluctuate due to shifting weather and historical variability:

Lake Superior: Currently 19 inches below the January 2020 record high and 16 inches above its 1926 record low.
Lake Michigan-Huron: Down 41 inches from its 2020 high but 26 inches above its 2013 low.
Lake Erie: 27 inches below its 1987 peak and 38 inches above its 1935 minimum.

Water levels go through a seasonal pattern. In the fall and early winter, lakes generally decrease because the colder temperatures cause more evaporation and cold air passes over the warmer lake waters. In the spring and early summer, water levels usually rise because there is more rainfall and melted snow runoff. The overall impact of precipitation, evaporation, and runoff on the lake is referred to as Net Basin Supply (NBS).

Outflow and Ice Conditions Raise Navigational Alerts

Outflow patterns indicate variability in lake-to-lake connections:

Outflows from Lake Superior through the St. Marys River are projected below average.
Lake Michigan-Huron’s outflows into St. Clair River and subsequent lakes show slightly above-average levels.

Mariners are urged to monitor conditions closely, especially during ice formation, which can affect water levels and navigation. The National Ice Center provides updated ice conditions for safe passage.

Staying Informed Amid Changing Conditions

The Army Corps of Engineers recommends stakeholders remain updated on water levels and related conditions, particularly those engaged in commercial or recreational activities on the lakes. For more information, visit the Great Lakes Information Network or the Corps’ Detroit District Homepage.

The U.S. Army Corps of Engineers Detroit District and Environment and Climate Change Canada collaborate to create monthly forecasts for Great Lakes water levels, covering a period of six months.

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