Frosty Fat Sass

The Frosty Fat Sass is an annual trail running and hiking event held in West Orange, New Jersey, at the South Mountain Reservation's Turtleback Rock Picnic Area. Scheduled for January 31, 2026, this 9th edition offers participants options to run or hike a 5K loop or take part in 3-hour or 6-hour timed events, including a new rucking division with weighted packs. The course features a mix of wide carriage roads and technical singletrack trails with rocky and root-filled sections, making it suitable for beginners and experienced trail enthusiasts.

The event fosters a fun, community atmosphere with family-friendly activities and supports the South Mountain Conservancy through fundraising. It is self-supported, with no aid stations or finishers' swag. Visit the organization's website for the most recent information.