Flathead Lake usually remains open across its main basin through winter. Ice forms more readily in bays and along sheltered shoreline, while a lake-wide freeze requires an unusually long spell of deep cold with little wind. Complete ice cover belongs to exceptional winters rather than the lake’s normal seasonal cycle. A deep, moving lake resists
Crater Lake normally remains largely open through winter even while deep snow accumulates around the caldera. A complete lake-wide freeze requires conditions far beyond an ordinary snowy winter: the National Park Service reports that the lake has not frozen over completely since 1949. Short-lived skim ice is a different phenomenon and can appear on calm
Yellowstone Lake normally develops complete seasonal ice cover rather than merely freezing along its shoreline. Its long observational record places ice-on near the end of December on average and breakup in late spring, but individual winters can depart substantially from those averages. Why such a large lake can still freeze completely Yellowstone Lake combines substantial
Lake Tahoe’s main basin does not develop seasonal whole-lake ice cover. Even during the cold 2022–23 winter, when Emerald Bay froze completely and ice appeared in marinas and shoreline pockets, the open lake itself remained unfrozen. Why the main lake stays open through winter Lake Tahoe has the geometry of a lake that stores a
Lake Winnipeg normally develops complete seasonal ice cover, but its north and south basins do not shed that ice at the same pace. Autumn freezing is closely synchronized across the lake; spring breakup stretches longer in the deeper north basin, so a single “ice-off date” can hide a multi-week spatial transition. Why spring breakup separates
Lac Saint-Jean normally develops a lake-wide winter ice cover, but the transition from open water to a continuous frozen surface is gradual. Nearshore ice can appear well before exposed parts of the lake lock up, and the spring “ice departure” record uses a defined open-water threshold rather than requiring every remaining piece of ice to
Lake Nipissing regularly develops complete seasonal ice cover, but its historical freeze date refers to whole-lake freeze-over rather than the first ice appearing along a shoreline or inside a sheltered bay. The record centers complete closure in early December and complete ice loss in late April, with enough year-to-year variation that neither boundary should be
Lake Champlain develops winter ice regularly, especially in sheltered bays, but the broad lake does not close every year. The National Weather Service listed a full closure on February 13, 2026, the first since March 8, 2019, after six consecutive winters without a listed closure. What “closed” means on Lake Champlain Lake Champlain has one
Lake of the Woods normally develops a persistent seasonal ice cover, with freeze-over centered on the turn from November to December and breakup extending from late April into May. The lake is large enough, and its bays, islands, narrows and open reaches different enough, that a single ice-on or ice-off date should be read as
Lake Athabasca normally develops complete seasonal ice cover. Ice formation begins during autumn, but the lake does not reach complete freeze-over at the moment the first ice appears. Environment Canada places the start of freeze-up in mid- to late October, with completion by mid-December. In spring, opening begins first at the western end, while complete