Ice is not weather, it is history. A cold morning tells you almost nothing. What matters is how much cold has accumulated since freeze up, and whether this winter is running ahead of or behind normal. This compares accumulated cold across six Michigan waters with a ten year station normal, while Great Lakes ice cover is compared with a 54 year climatology.

Season cold accumulation

The bar shows accumulated freezing degree days so far this season for each water. The marker is where a normal season sits on this calendar date. Ice growth follows the square root of accumulated cold, so this is the single most useful number for whether ice should be forming at all.

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Conditions by water

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What this site does and does not tell you

There are three separate things people mean when they ask about ice conditions, and only two of them can be answered with data from a distance.

• Has it been cold enough for ice to form? This is answerable, and it is what the accumulated cold number is for. It comes from real daily temperature records at a station near each water.
• Is there ice out there right now? Partly answerable on the Great Lakes, where NOAA publishes satellite derived ice cover. Not answerable on inland lakes, which have no comparable product, and the inland pages here say so.
• Is the ice safe where I want to stand? Not answerable. Not by this site, not by any site, not by a forum post from yesterday. Michigan DNR rejects the inch thickness rule entirely because ice does not form uniformly, and thickness can change by feet within a few yards.

The third question is the one that matters most and the only honest answer is a spud bar in your hands. Everything here is context for the drive, not permission to walk out.

The waters

Six waters, chosen because they carry most of Michigan ice fishing traffic and because they behave very differently from each other. A shallow wind exposed bay, a deep northern basin, a lake sitting on top of a river, and inland lakes with no satellite coverage at all.

Common questions about Michigan ice

Is the ice safe in Michigan right now?

Nothing on this page can tell you that, and no site can. Everything here is accumulated weather data and satellite observation, and none of it measures the ice under your feet. The Michigan DNR does not recognize a reliable inch thickness rule and states that ice on the bays of the Great Lakes will always be more fragile than ice on inland lakes. What accumulated cold can tell you is whether it has been cold enough, for long enough, for ice to have formed at all, and whether this winter is running ahead of or behind its ten year accumulated-cold normal. Separately, the parent Great Lake can be compared with its 54 year ice-cover climatology. Those are useful screens before you drive north and useless substitutes for testing. Test with a spud bar or auger every few steps, on every trip, including water you fished last week and found solid.

How much cold does it take to make ice?

Ice formation tracks accumulated cold rather than any single cold morning, which is why one hard overnight freeze in December means much less than people expect. The measure used here is accumulated freezing degree days: every day below freezing adds to a running total from freeze up, and that total is compared against a ten year station average for the same date. A shallow, sheltered inland lake locks up on a modest total. A wide, wind exposed body like Saginaw Bay needs far more, because wind keeps the water moving and mixing, and moving water sheds cold instead of holding it. That is why two waters a hundred miles apart sit at completely different stages in the same week, and why a single statewide ice number would be worse than none at all.

Which Michigan lakes have satellite ice cover data?

Only the Great Lakes waters have a satellite product, and the data used here is lake-wide rather than bay-specific. Saginaw Bay displays the Lake Huron average and Grand Traverse Bay displays the Lake Michigan average, so each is a directional parent-lake signal rather than an observation of that bay. Inland lakes have no comparable product. Nobody flies a satellite ice analysis over Houghton Lake or Mullett Lake, so for those waters the accumulated cold figure and the ten year station comparison are all there is. This is the most important limitation to understand about this page. On the Great Lakes it can describe whole-lake ice conditions. On inland lakes it can only say whether the weather has been cold enough that ice ought to have formed.

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