
RMRR Fall Marathon Training Series #3 is a running race on September 27, 2026 in Thornton, CO, with entry fees from $20 to $30.
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, 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 and aid stations. We’ll time your run, and winners of each distance will receive ribbons. We make it easy for you to work on your pace, nutrition, and hydration, 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 Platte River Trailhead Park, 88th & Colorado, Thornton, CO.
#1: Aug 30 - 10mi & 20mi
#2: Sep 13 - 20k & 30k
#3: Sep 27 - 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.
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
76°
Typical Low
44°
Chance of Rain
19%
Based on US Climate Normals data from Northglenn, 5 mi from the venue.
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.
Every finish line starts with a single decision. Claim your spot at RMRR Fall Marathon Training Series #3, put it on the calendar, and turn “someday” into a start date.
11
Days to train
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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.
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.
RMRR Fall Marathon Training Series #3
Sep 27, 2026