Great Lakes Experiences Rapid Early Winter Ice Growth Followed by a Late-December Thaw
LTJG Jared Doris, USN
NIC.PAO@noaa.gov
U.S. National Ice Center
December 29, 2025
Suitland, MD — The U.S. National Ice Center (USNIC) has been tracking the fast start to the Great Lakes ice season. USNIC and the Canadian Ice Service began the annual production of joint Great Lakes daily ice charts on 29 November 2025, following observations of ice formation in Black Bay (Lake Superior). Colder than normal temperatures were experienced through the first two weeks of December which led to unseasonably high ice coverage across the Great Lakes.
Great Lakes ice coverage was nearly 6% on 16 December. For comparison, the same date last year saw only approximately 1.5% ice cover. However, ice growth has stagnated in the last week as a warmer air mass moved into the Great Lakes region. Ice cover has fallen to below 5% as of 28 December. Despite this recent thaw, ice cover on the Lakes is still greater than last year.
Accurate and timely information on Great Lakes ice conditions is critical for both maritime safety and for the effective movement of cargo across the Lakes. The primary users of USNIC’s Great Lakes products are the U.S. Coast Guard (USCG) and the commercial interests that USCG icebreakers assist throughout the winter. These relationships, along with the accurate environmental intelligence are crucially important for the United States economy1,2. To access USNIC’s standard Great Lakes Products, visit: http://usicecenter.gov/Products/GreatLakesHome
http://usicecenter.gov/Products
https: //lcaships.com/wp-content/uploads/2021/01/Icebreaking-FAQs-.pdf
https: //lcaships.com/wp-content/uploads/2021/04/Great-Lakes-Winter-Commerce-Act.pdf
For more information, please contact:
National Ice Center
Command Duty Officer
Voice: (301) 943-6977
E-mail: nic.cdo@noaa.gov
Twitter: @usnatice
Facebook: @usnatice
The U.S. National Ice Center is a tri-agency center operated by the Navy, NOAA, and Coast Guard and provides global to tactical scale ice and snow products, ice forecasting, and related environmental intelligence services for the United States government.
