BestRacesroad · Half marathon · 15K · 5K · and 1 more
16th Annual Rock CF Rivers Half Marathon
Build your free race-day pace plan| Distances | Half marathon, 15K, 5K, Virtual run |
| Surface | road |
| Field size | 675 runners |
| Founded | 2012 (14 years) · from the race's own edition count |
| USATF certified | Yes |
| Boston qualifier | No |
From the race's RunSignup listing, with field size from its posted results, last updated September 23, 2026.
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Giveaways in MI
Win a free entry to 44th Annual Reeds Lake Resolution RunGrand Rapids, MI · free to enter · closes November 29, 2026 at 11:59 PM ESTRace-day weather
What the weather did on March 21 in each of the last 5 years, measured at Detroit Metro Airport, 11.1 miles from Grosse Ile.
| Year | High | Low | Rain |
|---|---|---|---|
| 2026 | 43°F | 34°F | none |
| 2025 | 54°F | 25°F | none |
| 2024 | 38°F | 19°F | none |
| 2023 | 57°F | 33°F | none |
| 2022 | 62°F | 38°F | none |
Daily highs and lows, not start-line temperatures: most races start in the cool of the morning, closer to the low. Source: NOAA National Centers for Environmental Information, GHCN-Daily.
Stay near Grosse Ile
Hotels and rentals in and around Grosse Ile, MI.
Preset to race weekend, Mar 20 – 22.
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Race Pace Analyzer beta
Build your 16th Annual Rock CF Rivers Half Marathon splits
This one already knows the course. Give it your goal time and it gives you every split to the finish, adjusted for this race's terrain and its usual race-morning temperature, plus a fueling plan and a check on whether the goal fits your fitness. It's free, and there's nothing to sign up for.
- Already loaded
- 3 distances
- ≈33°F on March race mornings
| Mile | Split | Elapsed |
|---|
Training paces for this goal
The everyday paces that build the fitness behind your goal, worked out from your target with the Daniels VDOT model. Save these for your next training block.
Treat these as a guide. Run easy days by feel, and adjust for heat, hills and how your legs feel that day.
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