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

[3] Most weather fronts originate in the Pacific Ocean, and 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.

During winter months, weather is usually cloudy, but, due to high pressure systems over the Pacific Ocean that intensify during summer months, there is often little or no cloud cover during the summer.

This King County, Washington state location article is a stub.