15TH Annual
15th Annual Rock CF Rivers Half Marathon & 5K
15th Annual Rock CF Rivers Half Marathon & 5K is a running race on March 21, 2027 in Grosse Ile, MI, with entry fees from $40 to $85.
- Date
- March 21, 2027 (195 days to go)
- Location
- 23270 E River Rd, Grosse Ile, MI
- Price
- $40–$85
- Sport
- Running
From the Organizer
THE ROCK CF RIVERS HALF MARATHON IS BACK!
Join us as we Outrun Cystic Fibrosis!
Sunday, March 22, 2026
Rock CF is hitting the island for the 15th Annual Rivers Half Marathon, 5K Run/Walk & NEW 15K!
Rock CF is a community, thousands strong, changing the face of what living with cystic fibrosis looks like and giving those living with CF the tools to not only survive, but thrive. 100% of all proceeds support the mission of the Rock CF Foundation.
Caps for 2026
Half Marathon Cap = 800
15K Cap = 300
5K Run/Walk Cap = 500
HALF MARATHON
Start Time: 8:00am
Start Location: Grosse Ile Middle School - 23270 E River Rd, Grosse Ile Township, MI 48138
Finish Location Grosse Ile Middle School - 23270 E River Rd, Grosse Ile Township, MI 48138
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15K
Start Time: 8:00am
Start Location: Grosse Ile Middle School
Finish Location: Grosse Ile Airport Area
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5K RUN/WALK
Start Time: 8:15 am
Start Location: Grosse Ile Airport (South of Naval Hangar)
Finish Location: Grosse Ile Middle School
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VIRTUAL RUN
We will be sending out packets the week of the race so that you can participate with us from wherever you are! Whether that be a walk around the block or a full half marathon, we can't wait to see what you accomplish. Be sure to tag us on our socials @LetsRockCF so we can share your journey and runs!
Events
Weather
Typical Conditions
It's too far out for a forecast, so here's what weather on this date is normally like in the area. A race day forecast will replace this as race week approaches.
Typical High
48°
Typical Low
30°
Chance of Rain
37%
Based on US Climate Normals data from Detroit Metro Ap, 12 mi from the venue.
Host City
About Grosse Ile, MI
City Elevation
594 ft
Nearest Airport
DTW
Detroit Metropolitan Wayne County Airport · 11 mi
Time Zone
Eastern Time
From Endurance Grid
Line up lodging and travel early to lock in your race weekend.
Race Location
Your Next Start Line
What Are You
Waiting For?
Every finish line starts with a single decision. Claim your spot at 15th Annual Rock CF Rivers Half Marathon & 5K, put it on the calendar, and turn “someday” into a start date.
195
Days to train
- Race
- 15th Annual Rock CF Rivers Half Marathon & 5K
- Date
- March 21, 2027
- Location
- 23270 E River Rd, Grosse Ile, MI
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From Endurance Grid
About This Sport
Endurance Grid is here to help you understand the sport, decide if it’s the right fit, and learn how to prepare. For course distances, logistics, and race-day specifics, always defer to the race organizer’s event page.
With running, there's a distance for every fitness level, a community at every start line, and nothing beats the feeling of crossing a finish line you trained for.
Running is an endurance sport that rewards consistency, and showing up every week compounds in ways that will surprise you.
Running
From 5K to marathon, running races are an accessible entry point into endurance sport. There's a distance for every fitness level and a community at every start line.
Coming Up
More Running races near Grosse Ile, MI
Frequently Asked Questions
What is the 15th Annual Rock CF Rivers Half Marathon & 5K?
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15th Annual Rock CF Rivers Half Marathon & 5K
Mar 21, 2027