Is there a maximum possible thickness for lake ice?

Ice between about 30 cm and 70 cm on a cottage-country lake is not unexpected under average freezing conditions. But there’s no maximum; in the Northwest Territories, lake ice can become several metres thick.

Of course, ice thickness anywhere varies from year to year depending on—no surprise—air temperature. Water depth and movement are important factors too. Deeper water takes longer to cool down, so ice forms more slowly. And water bodies with wind or currents have less ice, no matter how cold the air gets.

The ideal ice-forming conditions? Still air, constant low temperatures, and no snow. A layer of snow insulates the lake and keeps ice from thickening.