When Does Mcmahon Lake Freeze? Typical Ice-In Dec 11, Ice-Out Mar 25
Mcmahon Lake in Scott County, Minnesota usually freezes over around Dec 11, and usually has ice-out around Mar 25, based on Minnesota DNR ice observations recorded between 2017-2025. That works out to roughly 261 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 Mcmahon Lake
| Typical freeze-up (ice-in) | Dec 11 |
| Typical ice-out | Mar 25 |
| Earliest freeze-up on record | Dec 1, 2025 |
| Latest freeze-up on record | Jan 7, 2024 |
| Earliest ice-out on record | Mar 7, 2017 |
| Latest ice-out on record | Apr 30, 2018 |
| Open-water season | ~261 days |
| Winters observed | 15 |
| Location | Scott County, Minnesota |
These are dates, not an ice-safety reading
A typical freeze-up date tells you when Mcmahon 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 Mcmahon Lake has landed as early as Mar 7, 2017 and as late as Apr 30, 2018 — a spread of weeks around the Mar 25 median. Freeze-up has ranged from Dec 1, 2025 to Jan 7, 2024. 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. The full nutrient and algae breakdown for Mcmahon Lake is on the lake report.
Source: Minnesota DNR Climate Office ice-in / ice-out records, observations from 2017-2025.
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