RMRR Fall Marathon Training Series
- Date
- August 23 – September 20, 2026
- Distance
- 10 Mile · Other
- Price
- $20–$75
From the Organizer
RMRR provides full and half marathon training opportunities for runners of all abilities.
RMRR’s Marathon Training Series provides 10mi/20km and 20mi/30km races that are low cost, friendly, supported, and officially timed. All you need to do is focus on your running! The MTS fits well into training schedules for Colorado Springs, Boulderthon, Long View, Berlin, Chicago, Monumental (Indy), New York, and other fall full and half marathons.
Everyone is welcome to Marathon Training Series races: RMRR members, guests, training team members, everyone! The courses are well marked, with mile markers will help you gauge your time. We’ll time your run, and winners of each distance will receive ribbons. We make it easy for you to work on your pace, your nutrition and drinking, and getting everything ready for your big race.
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 24 - 10mi & 20mi
#2: Sep 7 - 20k & 30k
#3: Sep 21 - 10mi & 20mi
You are welcome to run 15mi, 25k, or another distance. Just let us know at the start.
RMRR Members receive a 25% discount. Discount taken when you check out. Your membership must be current.
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
88°
Typical Low
56°
Chance of Rain
22%
Based on US Climate Normals data from Northglenn, 5 mi from the venue.
Host City
About Thornton, CO
Population
142,878
as of 2023
City Elevation
5,347 ft
Nearest Airport
DEN
Denver International Airport · 16 mi
Time Zone
Mountain Time
From Endurance Grid
A mid-size host city. Enough lodging and amenities to keep race weekend easy, without big-city sprawl.
Your Next Start Line
What Are You
Waiting For?
Every finish line starts with a single decision. Claim your spot at RMRR Fall Marathon Training Series, put it on the calendar, and turn “someday” into a start date.
67
Days to train
- Race
- RMRR Fall Marathon Training Series
- Date
- August 23 – September 20, 2026
Coming Up
More Running races near Thornton, CO
Unicorn 5k (North)
1K · 5K · From $24 · E 108th Ave & Colorado Blvd
2 miles away
Summer Sizzler- Denver
1 Mile · 5K · 10K · Other · From $17 · Carpenter Park/Thornton Recreation Center Park
3 miles away
RMRR Fall Marathon Training Series #2
Other · From $20 · Riverdale Ballfields in Thornton
Less than a mile away
RMRR September 5k/10k
5K · 10K · From $10 · 9830 Riverdale Road
Less than a mile away
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 the most accessible entry point into endurance sport. There's a distance for every fitness level and a community at every start line.
Frequently Asked Questions (FAQs)
- What is the RMRR Fall Marathon Training Series?
- RMRR Fall Marathon Training Series is a running race held in Thornton, Colorado on August 23, 2026. It is one of the many endurance events listed on Endurance Grid, a multi-sport endurance event calendar covering running races, triathlons, HYROX, and more endurance sports across the United States. Find more running races near you or explore our sports guides to learn what race day actually feels like.
- When and where is the RMRR Fall Marathon Training Series?
- Sunday, August 23, 2026 in Thornton, Colorado at Riverdale Ballfields in Thornton. Check the event page for exact start times and wave schedules.
- How do I register for the RMRR Fall Marathon Training Series?
- Registration is handled through the event's registration page. Confirm pricing and distances there, and sign up.
RMRR Fall Marathon Training Series
Aug 23, 2026