Pinnacle Peak 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.

Pinnacle Peak is a 1,000-foot (300 m) extinct volcanic cinder cone rising up from the flat farmlands surrounding Enumclaw.

This flat terrain was created by the Osceola Mudflow that spread from nearby Mount Rainier approximately 5,600 years ago.

The steep, forested, one mile Cal Magnusson Trail is located on the north side of the peak.