Fog Signals were arguably even more important than lighthouses, aiding vessels in foggy, snowy, and otherwise adverse conditions when a light might be obscured. Fog bells had been in use for some time, but weren’t particularly effective. First installed at South Manitou in 1875 as an experiment, the 10-inch steam whistle became standard throughout the Great Lakes. South Fox got hers in 1895. This was replaced by an air diaphone (the familiar bee-oom of days past) in 1929. The South Fox Fog Signal was discontinued in 1954.

The Fog Signal Building is of wood frame construction, 22 feet by 40 feet, with two-inch diagonal planking, covered with a corrugated iron sheet metal. The walls between studs are filled with sawdust and lime insulation. The hip roof is constructed of corrugated steel. The building has several steel-sash windows. The main floor slab is poured concrete, located approximately two feet above grade.

In 1934, when the skeletal tower was erected, a cupola with an interior stairway was added, along with a catwalk to provide access to the skeletal tower. The catwalk was removed after the station was decommissioned.

The fog signal interior is sheaved with flat sheet metal. It consists of a large room which originally housed the steam-powered fog signal apparatus. It has a ceiling height of 15 feet. Of the two smaller rooms, one functioned as a coal storage room, while the other has shelving for tool storage. An internal stairway leads to the cupola.

Two permanent wood braces were installed in 2018 to secure the chimney stacks that were formerly supported by machinery. While this is not original, it was deemed necessary to secure the stacks and avoid undue weight on the roof,

The fog signal equipment is missing, except for some metal tanks and piping.

This short video shows the interior.