Ice-off, Yellowstone Lake

Yellowstone Lake usually freezes over by late December, and ice-off typically occurs by the last week of May. This cold mountain lake is North America’s largest at high elevation (over 7,000 feet), and together with its tributaries represents the last remaining stronghold for the native westslope cutthroat trout. May through July are especially important months to be wary of grizzly bears that fish the lake’s tributaries for spawning cutthroat.