When Does Prairie Lake Freeze? Typical Ice-In Nov 29, Ice-Out Apr 21
Prairie Lake in St. Louis County, Minnesota usually freezes over around Nov 29, and usually has ice-out around Apr 21, based on Minnesota DNR ice observations recorded between 2007-2018. That works out to roughly 222 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 Prairie Lake
| Typical freeze-up (ice-in) | Nov 29 |
| Typical ice-out | Apr 21 |
| Earliest freeze-up on record | Nov 19, 2018 |
| Latest freeze-up on record | Nov 29, 2007 |
| Earliest ice-out on record | Apr 12, 2015 |
| Latest ice-out on record | Apr 30, 2008 |
| Open-water season | ~222 days |
| Winters observed | 6 |
| Location | St. Louis County, Minnesota |
These are dates, not an ice-safety reading
A typical freeze-up date tells you when Prairie 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 Prairie Lake has landed as early as Apr 12, 2015 and as late as Apr 30, 2008 — a spread of weeks around the Apr 21 median. Freeze-up has ranged from Nov 19, 2018 to Nov 29, 2007. 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. Prairie Lake carries an overall water-quality grade of D — the full breakdown is on the lake report.
Source: Minnesota DNR Climate Office ice-in / ice-out records, observations from 2007-2018.