Sunday, March 21, 2027Grosse Ile, MI
16th Annual Rock CF Rivers Half Marathon
3 events
- 15K15KRoadStarts 8:00 AM
- Half MarathonHalfRoadStarts 8:00 AM
- 5K Run/Walk5KRoadStarts 8:15 AM
Location
Approximate, from the race's ZIP code.
Typical race-day weatherGood weather · 75/100
- High / low
- 45° / 31°F
- 7° / 0°C
- Humidity
- 78%
- Dew point 31°F
- Chance of rain
- 37%
- Wind
- 12 mph
- Average
- Usually cold for a half marathon: about 36°F while racing.
- Rain on about 37% of days around this date.
- Often windy: about 12 mph on average.
Averages for this area and time of year over the last 20 years, from NASA POWER data. Not a forecast.
Past results
- 10% fasterFinish times are typically 10% faster than at other half marathons.2 years, 1,374 finishers; men and women compared separately.
- Typical timesFinish times are typical for 5Ks.2 years, 788 finishers; men and women compared separately.
- Typical timesFinish times are typical for 15Ks.1 year, 186 finishers; men and women compared separately.
| Year | Event | Finishers | Median | Men | Women |
|---|---|---|---|---|---|
| 2026 | Half Marathon · Half | 672 | 1:57:09 | 1:49:23 | 2:04:43 |
| 2026 | 15K · 15K | 186 | 1:36:48 | 1:28:06 | 1:40:47 |
| 2026 | 5K Run/Walk · 5K | 399 | 35:35 | 32:54 | 38:49 |
| 2025 | Half Marathon · Half | 702 | 1:58:10 | 1:52:49 | 2:03:33 |
| 2025 | 5K Run/Walk · 5K | 389 | 37:00 | 32:31 | 39:08 |
Median finish times from results published on RunSignup. Keyrace keeps only these summaries, never individual results. A fast or slow field affects times as much as the course does.