Great Lakes ice forecast: Forecasters predict turnaround from 2024 record low season

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MILWAUKEE — A cool December may be priming the Great Lakes for a starkly different ice season after scientists saw a record-low level of ice cover this year, according to a new forecast.

The U.S. National Ice Center released its 2024-2025 seasonal outlook, predicting slightly below to near normal ice conditions across the Great Lakes — a turnaround from last season’s record-breaking absence of ice.

This year, average ice cover across all five lakes was 4.3%, which was the lowest on record since scientists began tracking it more than 50 years ago, according to data from the National Oceanic and Atmospheric Administration. The 2023 season was the fourth lowest on record.

December sets the stage for ice formation. That's when cold, arctic air starts to cool the lakes, allowing ice to form in some of the bays and inlets. December 2023 was the warmest on record for much of the Great Lakes region, leading to the record-low ice year.

So far, this December has been much colder, which will likely help cool and prime the Great Lakes so ice can build.

Here’s what to know about the 2024-2025 ice forecast:

Near normal ice conditions predicted across the Great Lakes

The ice center forecasts slightly below normal to near normal ice cover for all of the lakes. Here are the predictions:

• Lake Superior: Near to slightly above normal temperatures are forecast for January and February. Slightly below normal ice conditions. 
• Lake Michigan: Near to slightly above normal temperatures are forecast for January and February. Slightly below normal ice conditions.
• Lake Huron: Above normal temperatures are forecast for January and February. Slightly below normal ice conditions are forecast.
• Lake Erie: Slightly above normal temperatures are forecast for January and February. Slightly below normal ice conditions are forecast.
• Lake Ontario: Slightly above normal temperatures are forecast for January and February. Near normal ice conditions are forecast.

Ice cover is declining due to climate change

Ice cover in the Great Lakes has been declining for the past five decades due to climate change. There will be extreme year-to-year fluctuations, as evidenced by the near-record lows followed by near-record highs seen in the last decade.

But the region is seeing less high-ice years, as roughly 65% of the last 26 years have had below-average ice.

The 2024 ice season was the second time average ice cover across the Great Lakes did not reach 5%. The first time was in 2012, when it hit 4.8%. (The third lowest was 7% in 2002.)

Lakes Michigan and Superior hit historic lows as well, with average daily ice cover at 4.4% and 2.6%, respectively.

Last year’s mid-January cold snap allowed some ice to build. Across the Great Lakes, maximum ice cover reached 16% on Jan. 22, the fourth lowest annual maximum on record. Lake Michigan hit a high of 18%, while Lake Superior maxed out at 12% ice cover.

Great Lakes ice maintains ecosystem health, recreation, infrastructure

The impacts of low ice cover are far-reaching, and what happens in the winter matters for the rest of the year. 

Here's how ice cover benefits the Great Lakes:

• Lake levels: If lake levels are too low, it can lead to lower lake levels later in the summer as the lakes warm faster, leading to more evaporation. But lake levels also depend on other factors such as rainfall.
• Lake-effect snowstorms: Late fall and early winter is primetime for lake-effect snow when the waters are still relatively warm, and have little to no ice cover. Lake-effect snowstorms occur when cold, dry air travels over open water, sucking up moisture that is released when the air mass hits land.
• Shoreline erosion and infrastructure: Ice tempers waves during winter storms. Waves are larger when there is less ice, which can lead to lakeshore flooding and erosion. Ice helps protect infrastructure such as intake valves during storms as well. 
• Fisheries: Ice protects fish populations that spawn in the fall in the nearshore areas. Ice protects fish eggs by suppressing winds and waves that can stir up the sediment.
• Food web: Less ice and warmer waters can cause phytoplankton − microscopic plant-like organisms that form the base of many aquatic food webs − to bloom earlier than the zooplankton that feed on them. If there are no zooplankton around, there can be a ripple effect up the food chain, especially on the fish that depend on zooplankton.
• Water quality: Warmer waters and less ice can create the perfect conditions for blue-green algae blooms later in the summer. These blooms suck up oxygen and block sunlight, which makes it harder for aquatic life to survive.

Caitlin Looby is a Report for America corps member who writes about the environment and the Great Lakes. Reach her at clooby@gannett.com, follow her on X @caitlooby and learn more about her reporting.