When Does Lake Vermilion Freeze? Ice-In Dates

Short answer: in the Minnesota DNR record, Lake Vermilion has locked up between November 6 and December 13. The earliest is 1991. The latest is 1998. The DNR median is November 28. The record has 31 entries across 24 years, from 1983 to 2023. The gaps are large, so treat these dates as a rough window and not a promise for any year.

No ice is ever 100% safe. Check it yourself.

An ice-in date is not a green light. It is the day an observer says the lake froze over and stayed that way. It says nothing about thickness where you plan to stand.

What the records show

The DNR State Climatology Office keeps the state's lake ice-in records. Observers and state programs report them. Here is the Lake Vermilion file (DNR lake ID 69037800, St. Louis County).

• Entries: 31, from 24 different years.
• Span: first entry November 25, 1983. Last entry November 28, 2023.
• Earliest ice-in: November 6, 1991.
• Latest ice-in: December 13, 1998.
• Median: November 28. The DNR calculates this from dates since 1950. The median of all 31 entries comes out the same.

Lake Vermilion is a big lake. The DNR lists it at about 39,000 acres, with a maximum depth of 76 feet and about 341 miles of shoreline. The feed does not say which part of the lake each observer watched, so treat a single date as a lake-wide idea, not a bay-by-bay one.

The DNR also has a separate record named East Vermilion (ID 69037801) with one entry, November 28, 2024. We keep it out of the stats above because it is a different record from the main Vermilion file.

Lake Vermilion ice-in dates

Some years have more than one entry from different sources. Where they differ, every date is shown.

The record is thin in places. There are no entries in the main Vermilion file for 1984 to 1990, 2005, 2008, 2012, 2014 to 2019, 2022, 2024, or 2025. The 2001 Dec. 7 date appears twice in the feed. We count it once in the table and twice in the 31 entries.

Fourteen of the 24 years have all their dates between November 12 and November 30. Nine years have a December date, from December 1 to December 13. One year, 1991, is the lone early outlier at November 6.

What "ice in" means here

The DNR defines ice-in for its citizen observers as the day the entire lake is frozen over and the ice cover remains through winter. Observers do not report ice thickness.

The DNR says plainly that it does not measure ice thickness on Minnesota lakes. It also says ice-in dates should not be used to track ice thickness for recreation. And it does not post the current year's ice-in dates in real time, for safety, because the ice cover may not be permanent for the season.

So an ice-in date tells you roughly when a lake locked up. It does not tell you what is safe to walk on today.

Ice thickness minimums (Minnesota DNR guideline)

These are the DNR guidelines for new, clear ice only:

• Under 4 inches: stay off.
• 4 inches: ice fishing or other activities on foot.
• 5 to 7 inches: snowmobile or small ATV.
• 7 to 8 inches: side-by-side ATV.
• 9 to 10 inches: small car or SUV.
• 11 to 12 inches: medium SUV or small truck.
• 13 inches: medium truck.
• 16 to 17 inches: heavy-duty truck.
• 20 inches or more: heavy-duty truck with a wheelhouse shelter.

White ice is only about half as strong as new, clear ice. The DNR says to double these numbers on white ice. Ice is seldom the same thickness across a lake. The DNR notes it can be two feet thick in one place and one inch thick a few yards away. The DNR lists currents, narrow areas, bottlenecks, snow, and sun and shade among the things that change ice strength.

Parked vehicles need more. The DNR says to park cars at least 50 feet apart and move them every two hours.

How to check current ice

1. Do not rely on a date. Check thickness where you are standing.
2. Drill a hole. Measure clear ice, not slush or white ice.
3. Drill again every few steps. Ice changes fast.
4. Stay off the edges of pressure ridges, cracks, and open water.
5. Wear a flotation device and carry picks and a rope.
6. Tell someone where you are going and when you will be back.

The DNR says new ice is usually stronger than old ice, and that four inches of clear, newly formed ice may support one person on foot.

Do not drive onto ice because someone else did. Measure for your own load.

We did not find an official source for when hardwater season or plowed roads start on Lake Vermilion, so we do not give a date. Check the DNR and local notices for current conditions.

No ice is ever 100% safe. Check it yourself.

What we will update

Iceline will update this guide as new Lake Vermilion entries are added to the DNR record. Until then, treat mid November as the time to start watching, and treat any first ice as unproven until you measure it.

FAQ

When does Lake Vermilion freeze?

In the DNR record it has frozen between November 6 and December 13, with a median of November 28. The record covers 24 years from 1983 to 2023. That is not a promise for any year.

What is the earliest Lake Vermilion has frozen?

November 6, 1991. The latest on file is December 13, 1998. The record has gaps, so an earlier or later date is possible.

How thick should ice be to walk on?

The Minnesota DNR guideline is 4 inches of new, clear ice for ice fishing or other activity on foot. Use 5 to 7 inches for a snowmobile or small ATV. Double the numbers on white ice. Check it yourself.

Does the ice-in date mean the lake is safe?

No. It marks when observers saw the lake freeze over. The DNR says not to use ice-in dates to judge thickness.

Does the DNR measure ice thickness on Lake Vermilion?

No. The DNR says it does not measure ice thickness on Minnesota lakes. Your safety is your responsibility.