Mountain Weather: In the mountains, a clear sunny day can quickly become stormy, bringing lightning, hail and snow at higher elevations. Since storms often develop by early afternoon, plan hikes so you reach the highest point before noon and descend soon after. Always take rain gear!

Daytime summer temperatures are usually 70 to 80 degrees F. June can be cool and rainy while July and August tend to be drier, but afternoon thundershowers are common. High water from spring runoff can make stream crossings hazardous and some trails wet and muddy until mid-July. Consult authorities for current conditions before venturing into the backcountry.

The ice cover on Yellowstone Lake normally does not break up until late May or early June. Lewis and Shoshone Lakes usually lose their ice by the second or third week in June. The water temperatures of these lakes, even in the summer, are typically 40 to 50 degrees F.

View a close-up view of a portion of the trail map.

Be alert for bears in geyser basins in spring and early summer. Do not travel through thermal areas after dark. Stock are not permitted in thermal areas. To swim, bathe, or soak in waters that are entirely of thermal origin is prohibited. No food or smoking is allowed in thermal areas.

Damming, altering and puttting rocks, sticks or any object into thermal features are prohibited.