Rmrr Fall Marathon Training Series #3
About this race
RMRRs Marathon Training Series (MTS) races are low cost, friendly, supported, accurately measured, well marked, and timed. Each MTS has 10mi & 20mi, or 20k & 30k options. All you need to do is focus on your running!
The MTS fits well into training schedules for Colorado Springs, Boulderthon, Long View, Chicago, Monumental (Indy), New York, and other fall full and half marathons.
MTS#3 offers 10mi & 20mi options (we can accommodate almost any distance in between).
Please note that for everyone's safety, dogs or running strollers are not permitted on our courses. Thanks for understanding.
The races begin at 7 am at Riverdale Ballfields at 9830 Riverdale Road in Thornton Colorado.
#1: Aug 25 - 10mi & 20mi
#2: Sep 8 - 20k & 30k
#3: Sep 22 - 10mi & 20mi
RMRR Members receive a $5 discount off individual races and $15 off the 3-race bundles. Discount taken when you check out. Your membership must be current.
Pick your distance
Running
RMRR Fall Marathon Training Series #3 - 10 Mile
Out-n-back once.
RMRR Fall Marathon Training Series #3 - 20 Mile
Out-n-back twice.
Typical race-day weather
Based on 5 years of Open-Meteo archive data for this event's race dates in Thornton, plus the 3 days either side.
The sun rises at 6:52 AM and sets at 6:49 PM local time (MDT) in Thornton on September 27, 2026 — 11h 56m of daylight.
Course
No course map published yet.
The organizer hasn't released a route for this event, and we don't publish guesses. If you're the organizer, send us a GPX file and we'll draw the profile.
Reviews
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Other races near Thornton
Different organizers, within 40 miles, in the next three months
Rmrr Fall Marathon Training Series #2
I Can 5k
I Ain't Scared (of 5k)
NW Open Spaces 5k XC PR Challenge
🏃 Plan Your Next Race in Thornton
Find upcoming events by distance:
- Thornton 5K Races 7 races
- Thornton Running Calendar 2026 12 races
Where this page comes from. Race details were last updated on . We re-check listings regularly and again in the week before race day.
- Entries, prices, waves and inclusions — the event's official registration page
- Temperature and humidity — Copernicus ERA5 reanalysis via Open-Meteo (CC BY 4.0)
- Elevation and terrain relief — Copernicus DEM GLO-90, ESA (CC BY 4.0)
- Comparisons and counts — Race Discovery calendar, 12 Thornton events
Spotted something wrong? Tell us and we'll fix it.