When Does Zumbro Lake Freeze? Typical Ice-In Dec 1, Ice-Out Mar 31
Zumbro Lake in Olmsted County, Minnesota usually freezes over around Dec 1, and usually has ice-out around Mar 31, based on Minnesota DNR ice observations recorded between 2014-2018. That works out to roughly 245 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 Zumbro Lake
| Typical freeze-up (ice-in) | Dec 1 |
| Typical ice-out | Mar 31 |
| Earliest freeze-up on record | Nov 13, 2014 |
| Latest freeze-up on record | Dec 28, 2015 |
| Earliest ice-out on record | Feb 22, 2017 |
| Latest ice-out on record | Apr 25, 2018 |
| Open-water season | ~245 days |
| Winters observed | 51 |
| Location | Olmsted County, Minnesota |
These are dates, not an ice-safety reading
A typical freeze-up date tells you when Zumbro 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 Zumbro Lake has landed as early as Feb 22, 2017 and as late as Apr 25, 2018 — a spread of weeks around the Mar 31 median. Freeze-up has ranged from Nov 13, 2014 to Dec 28, 2015. 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. Zumbro 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 2014-2018.