16th Annual Rock CF Rivers Half Marathon
Updated
Sunday, March 21, 2027, first start 8:00 AM, in Grosse Ile (7800 Grays Dr). Distances: 5K, 15K, Half marathon. Entry from $40 to $90.
Course and race notes
The 16th Annual Rock CF Rivers Half Marathon, 15K, and 5K is coming back to the island of Grosse Ile, Michigan on Sunday, March 21st, 2027 for all to come and help us outrun cystic fibrosis!
In the organizer's words, from the race's own listing.
Race details
Date
Sunday, March 21
2027 · in 134 days
Start time
8:00 AM
Earliest wave
Course
Road or path
Paved course
Distances
5K15KHalf marathon
Price
$40 to $90
Plus the platform's processing fee
No price increase published
Registration
Open
Online signup closes Sun Mar 21 (in 134 days)
Opened Sep 18, 2026
Race day in Grosse Ile
Weather
48° / 30°F
Typical high and low for March 21, with a 37% chance of rain.
NOAA 1991–2020 climate normals, Detroit Metro Airport, MI (11.8 mi away). Averages, not a forecast; a forecast appears here a week out.
Daylight
7:36 AM – 7:44 PM
Sunrise and sunset on Sunday. The first start is 24 minutes after sunrise.
Calculated for the race location.
Near the start
Pin from the race's listed address. The start line can differ; check the race website for the course map. Directions
Parking
2 public lots and garages within 0.6 mi, the nearest 0.4 mi away.
Places to eat
- Island Coney restaurant0.2 mi
- Galindos restaurant0.5 mi
Distances are straight-line from the race address. Check the race website for official parking.
Plan your trip
For the night before, Sat Mar 20
Where to stay
See all places to stay near Grosse Ile, MI ↗
Prices checked November 4, 2026 and can change. Confirm on the booking site before you book. We may earn a commission at no cost to you.
Trip cost
Add what you'll actually pay. It stays in this browser.
Total $0
Race entry starts at the lowest listed price, before the platform's fee.