When Does Koronis Lake Freeze? Typical Ice-In Dec 1, Ice-Out Apr 14
Koronis Lake in Stearns County, Minnesota usually freezes over around Dec 1, and usually has ice-out around Apr 14, based on Minnesota DNR ice observations recorded between 1977-2023. That works out to roughly 231 days of open water a year. These are typical dates across many winters, not a forecast — individual years swing by weeks in either direction.
Ice record for Koronis Lake
| Typical freeze-up (ice-in) | Dec 1 |
| Typical ice-out | Apr 14 |
| Earliest freeze-up on record | Nov 29, 1977 |
| Latest freeze-up on record | Dec 6, 1986 |
| Earliest ice-out on record | Apr 3, 2004 |
| Latest ice-out on record | Apr 28, 2023 |
| Open-water season | ~231 days |
| Winters observed | 10 |
| Location | Stearns County, Minnesota |
These are dates, not an ice-safety reading
A typical freeze-up date tells you when Koronis Lake has usually iced over — it does not tell you the ice is safe, and we hold no thickness measurement for this or any lake. The Minnesota DNR is explicit that no ice is ever completely safe: thickness varies across a single lake, and current, springs, aerators, and insulating snow all weaken it. Ice that held a truck last week may not hold a person today.
Read the ice-thickness guidelines before going out, and check current conditions with the Minnesota DNR ice-safety page and local bait shops, which track conditions lake by lake.
How much the timing varies
Ice-out on Koronis Lake has landed as early as Apr 3, 2004 and as late as Apr 28, 2023 — a spread of weeks around the Apr 14 median. Freeze-up has ranged from Nov 29, 1977 to Dec 6, 1986. That year-to-year swing is why a median date is a planning tool, not a schedule. Freeze-up is driven by accumulated cold after the lake turns over in fall; ice-out by late-winter air temperature, sun angle, and how much snow sits on top of the ice reflecting it. Koronis Lake carries an overall water-quality grade of C — the full breakdown is on the lake report.
Source: Minnesota DNR Climate Office ice-in / ice-out records, observations from 1977-2023.