Mount Jupiter is a mountain summit in the Olympic Mountains and is located in Jefferson County of Washington state. It is situated in The Brothers Wilderness on land managed by Olympic National Forest. Mount Jupiter is easy to identify from Seattle, since it appears as the prominent peak between The Brothers and Mount Constance. The Jupiter name was applied by the Seattle Press Expedition in an effort to link the peak with the Greco-Roman mythological names associated with Mount Olympus. Jupiter was a Roman god on Olympus.