Dewey Peak is a 6,710-foot (2,045 m) summit located on the shared border of Mount Rainier National Park and William O. Douglas Wilderness.

Dewey Peak is located in the marine west coast climate zone of western North America.

[3] Most weather fronts originating in the Pacific Ocean travel northeast toward the Cascade Mountains.

As a result, the west side of the Cascades experiences high precipitation, especially during the winter months in the form of snowfall.

[3] Because of maritime influence, snow tends to be wet and heavy, resulting in high avalanche danger.