18th Annual F^3 Lake Half Marathon & 5k
About this race
The 18th Annual F^3 Lake Half Marathon & 5k is Chicago's Original Winter Half Marathon. Each year, thousands of runners flock to this community-built event, gathering in the warmth of Soldier Field's United Club before tackling wind & weather along a lakefront course that features splits every 5km. A must for anyone preparing for a spring marathon or just resolving to stay fit throughout the new year. F^3 sold out in 2016-2020 and 2023-present.
Every registrant will once again receive one of our great hoodies and a medal! We will return to the warm confines of Soldier Field's United Club! The UC opens at 8 a.m. Gear check is available. The half marathon starts at 10:01 a.m. and consists of self-seeded waves in quick succession. The 5k is scheduled for 10:29 a.m. Courses close at 1:30 p.m.
After the race, head to Weathermark Tavern for the afterparty! 1503 S. Michigan Ave. Free participant photos are always uploaded to flashframe.io
Join fellow runners on January 31, 2026 for the 18th Annual F^3 Lake Half Marathon & 5k. It's a fantastic Half-Marathon, 5K featuring a flat and fast course in Chicago.
Pick your distance
Running
Half Marathon
Winter Half Marathon on a plowed & salted path. Finisher Medals. Hoody. Splits at 5km, 10km, 10M. Prize Money to top 5 Open Women & Men. Prize Money to top 3 Masters Women & Men. Pace groups provided by CES. (1:30, 1:40, 1:50, 2:00, 2:10, 2:20, 2:30, 2:45, 3:00) Six aid stops along the route. (2.5, 3.6, 6, 8.1, 10.5, 11.6) Gather in the United Club! Post-race party at Weathermark Tavern!
5k
Winter 5k on a plowed & salted path. Finisher Medals! Hoody! Post-race party at Weathermark Tavern! Gather in the United Club!
Weather Overview
These values reflect historical conditions on the race dates in Chicago in 2026, from Open-Meteo archive data.
About Chicago
18th Annual F^3 Lake Half Marathon & 5k takes place in Chicago, Illinois, United States. The local timezone is America/Chicago.
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Race information has been sourced from the event's official website and other publicly available resources. For the most up-to-date details, please refer to the official website directly. If you notice any incorrect or missing information, don't hesitate to reach out to us by email.