Green Mountain is located in the marine west coast climate zone of western North America.

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

[4] The history of the formation of the Cascade Mountains dates back millions of years ago to the late Eocene Epoch.

[5] During the Pleistocene period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured the landscape leaving deposits of rock debris.

Uplift and faulting in combination with glaciation have been the dominant processes which have created the tall peaks and deep valleys of the Cascade Range.