[3][4][5] Green Mountain is located in the marine west coast climate zone of western North America.

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

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

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

[6] Due to its temperate climate and proximity to the Pacific Ocean, areas west of the Cascade Crest very rarely experience temperatures below 0 °F (−18 °C) or above 80 °F (27 °C).