How did this most recent winter’s (2025-26) ice season compare?
After a warm start to November, most Minnesota lakes froze during a stretch of below average temperatures between late November and mid-December. Compared to recent winters, ice formation was fast in southern Minnesota and slow in many northern Minnesota lakes.
A frigid late-January cold snap helped lake ice survive a very warm February and most of a warm March, but ice breakup was still faster than recent winters in southern Minnesota. A cool April and start of May slowed ice breakup dramatically across northern Minnesota.
The maps below show this winter’s ice formation dates, ice breakup dates and ice duration in the context of our recent memory (2017-2026) and a colder historical period (1950-1959).
This winter’s ice formation dates in the context of our recent memory (2017-2026) and a colder historical period (1950-1959). Click here to view the data table.
This winter’s ice breakup dates in the context of our recent memory (2017-2026) and a colder historical period (1950-1959). Click here to view the data table.
This winter’s ice breakup dates in the context of our recent memory (2017-2026) and a colder historical period (1950-1959). Click here to view the data table.
What are the long-term trends?
The methods of Walsh et al. 2025 allow us to look at long-term trends in lake ice duration, formation date, and breakup date. Long-term trends across the data period (1949-2026) show later ice formation, earlier ice breakup, and shorter total winter ice duration.
While the general trend is towards less ice, year-to-year variation has increased in recent decades. Below is an example from Green Lake in Kandiyohi County. While ice breakup dates are on average trending downwards, year-to-year ice breakup has swung between late and unprecedentedly early in recent years.
What are the shorter-term trends, over the past decade?
Below are two sets of graphs that compare a given year’s ice breakup dates with the average ice breakup or formation date of the past decade. Ice formation and breakup are very variable year-to-year and across the state.
Explore the data
Explore the full dataset of ice in, ice out, and duration below. Long-term statistically modeled trends are compared to observations in lakes with sufficient observations. Look up individual lakes in the search bar in the upper-right corner. Figures are downloadable via links.
Suggested resources
This webpage is just the latest Minnesota lake ice data explorer. Visit these sites to learn even more about lake ice and how it is changing:
- Minnesota DNR Lake Ice Out/Ice In Dates
- The most up-to-date info
- MPCA Surface Water Data Dashboard
- Visualizing lake ice changes within a larger lake context
- Minnesota Sea Grant’s Minnesota Lakes Thaw Tracker
- Estimate when ice will be gone from your favorite lake
The date of lake ice formation and duration are examples of “phenology,” or the timing of seasonal events. Similar to this page, the National Phenology Network tracks changes in plant-based spring phenology events and compares them to long-term averages.
FAQ
How can I become a lake ice observer?
It’s easy! Read the DNR guidelines on how “ice in” and “ice out” conditions are defined, then send your reports to the MN DNR State Climatology Facebook Page, or email Assistant State Climatologist Pete Boulay directly at [email protected]. More information on the definition of ice on and ice off can be found at the Minnesota Pollution Control Agency.
What does “typical” mean?
Here “typical” denotes the long term trends found using the methods of Walsh et al. 2025. As of 2026 these trends are largely linear for lakes across the state, so the end points of the statewide linear trend are used to denote 1949 and present-day typical lake ice. This strong statistical relationship for lakes across the state is also what allows us to define meaningful averages for only a decade of data, allowing us to compare the most recent decade (2017-2026) to the historical period (the 1950s), even for lakes where observations are sparse.
How is the data quality controlled?
The State Climatology Office carefully reviews observations to fix errors like incorrect lake IDs or impossible dates. While there is no universal definition of “ice on” and “ice off” conditions, a key factor that makes this dataset so useful is consistent recordkeeping on a given lake. For example, Lake Minnetonka ice out is declared when the lake is safely navigable, while a report of “this was the first morning I didn’t see any ice while I was out walking my dog” would work just fine for another lake.
When and how often is this site updated?
This webpage is scheduled to be updated in late May or early June each year, several weeks after the final lakes in northern Minnesota have lost their ice.