Upcoming Races In Colorado, US in September, 2025

Featured Races Get Seen

Be the first race runners see — and grow your registrations. Put your race at the top.

Feature Your Race

Learn how to feature your race

Labor Day Half Marathon

Parker, CO

Monday, September 1st, 2025

Half

10K

Fast

View details for race Labor Day Half Marathon

Oak Creek No Fun Run

Oak Creek, CO

Monday, September 1st, 2025

View details for race Oak Creek No Fun Run

3rd Annual Roost Rebellion Relays

Denver, CO

Wednesday, September 3rd, 2025

View details for race 3rd Annual Roost Rebellion Relays

HRCA Wildcat Mountain Trail Races

Littleton, CO

Saturday, September 6th, 2025

10 Miles

10K

Trail

View details for race HRCA Wildcat Mountain Trail Races

Nielson Challenge

Colorado Springs, CO

Saturday, September 6th, 2025

View details for race Nielson Challenge

RexRun For PAWSitivity 2025 5K Trail Run/Walk

Aurora, CO

Saturday, September 6th, 2025

1 Mile

Trail

View details for race RexRun For PAWSitivity 2025 5K Trail Run/Walk

2025 Lake Nighthorse Triathlon - Sprint and Ol...

Durango, CO

Saturday, September 6th, 2025

View details for race 2025 Lake Nighthorse Triathlon - Sprint and Olympic

Black Squirrel Half Marathon

Bellvue, CO

Saturday, September 6th, 2025

Half

Trail

View details for race Black Squirrel Half Marathon

Cirque Series - Arapahoe Basin, CO

Keystone, CO

Saturday, September 6th, 2025

Trail

View details for race Cirque Series - Arapahoe Basin, CO

52nd Annual Imogene Pass Run

Telluride, CO

Saturday, September 6th, 2025

1 Mile

Trail

View details for race 52nd Annual Imogene Pass Run

Rebel Run 5k

Denver, CO

Sunday, September 7th, 2025

View details for race Rebel Run 5k

Buffalo Bicycle Classic

Boulder, CO

Sunday, September 7th, 2025

Ultra

View details for race Buffalo Bicycle Classic

RMRR September Trophy Series

Thornton, CO

Sunday, September 7th, 2025

10K

Fast

View details for race RMRR September Trophy Series

RMRR Fall Marathon Training Series #2

Thornton, CO

Sunday, September 7th, 2025

Ultra

View details for race RMRR Fall Marathon Training Series #2

Conservation Colorado 5k

Denver, CO

Sunday, September 7th, 2025

View details for race Conservation Colorado 5k

Honey Bee Hustle

Loveland, CO

Sunday, September 7th, 2025

View details for race Honey Bee Hustle

Flyin' Lion 5K

Littleton, CO

Sunday, September 7th, 2025

View details for race Flyin' Lion 5K

Denver Rocks Run 5K/10K

Denver, CO

Sunday, September 7th, 2025

View details for race Denver Rocks Run 5K/10K

National Chocolate Day: Run for Chocolates DENV...

Centennial, CO

Saturday, September 13th, 2025

10K

Half

View details for race National Chocolate Day: Run for Chocolates DENVER/AURORA

Highland Homecoming 5k Run & Walk

Ault, CO

Saturday, September 13th, 2025

View details for race Highland Homecoming 5k Run & Walk

Jungle Dash

Loveland, CO

Saturday, September 13th, 2025

1 Mile

View details for race Jungle Dash

Flying Falcon Downhill Mile

USAF Academy, CO

Saturday, September 13th, 2025

1 Mile

View details for race Flying Falcon Downhill Mile

Spooky Sprint - Colorado Springs

Colorado Springs, CO

Saturday, September 13th, 2025

10K

View details for race Spooky Sprint - Colorado Springs

DESERT'S EDGE TRIATHLON SERIES

Fruita, CO

Saturday, September 13th, 2025

View details for race DESERT'S EDGE TRIATHLON SERIES

2024 Spirit of the Valley 5k

Grand Junction, CO

Saturday, September 13th, 2025

View details for race 2024 Spirit of the Valley 5k

Valkyrie Ultra Heptathlon

Durango, CO

Saturday, September 13th, 2025

Trail

View details for race Valkyrie Ultra Heptathlon

All-Out Fall Fest

Westminster, CO

Saturday, September 13th, 2025

Half

10K

Trail

View details for race All-Out Fall Fest

The Denver 5k

Denver, CO

Saturday, September 13th, 2025

View details for race The Denver 5k

Historic Elizabeth Main Street 5K & Family Colo...

Elizabeth, CO

Saturday, September 13th, 2025

1 Mile

View details for race Historic Elizabeth Main Street 5K & Family Color Run

Trail Sisters Women's Half Marathon & 10k

Buena Vista, CO

Saturday, September 13th, 2025

Half

10K

Trail

View details for race Trail Sisters Women's Half Marathon & 10k

Break Your Neck: Walk, Run, or Roll

Pueblo, CO

Saturday, September 13th, 2025

View details for race Break Your Neck: Walk, Run, or Roll

Parker Parks and Recreation So Long to Summer 5...

Parker, CO

Saturday, September 13th, 2025

10K

View details for race Parker Parks and Recreation So Long to Summer 5K/10K

Muddy Dash | Denver

Dacono, CO

Saturday, September 13th, 2025

View details for race Muddy Dash | Denver

Healthy Kids Running Series Fall 2025 - Trinida...

Trinidad, CO

Sunday, September 14th, 2025

View details for race Healthy Kids Running Series Fall 2025 - Trinidad, CO

9/11 Heroes Run - Denver, Colorado

Denver, CO

Sunday, September 14th, 2025

1 Mile

View details for race 9/11 Heroes Run - Denver, Colorado

Sloan's Lake Search Party (SLSP) Marathon Hourl...

Denver, CO

Sunday, September 14th, 2025

Marathon

View details for race Sloan's Lake Search Party (SLSP) Marathon Hourly Loop Race!

Spooky Sprint - Denver

Denver, CO

Sunday, September 14th, 2025

10K

1 Mile

View details for race Spooky Sprint - Denver

Fall Equinox

Fort Collins, CO

Sunday, September 14th, 2025

Marathon

Half

Fast

View details for race Fall Equinox

Spooky Sprint - Denver

Littleton, CO

Sunday, September 14th, 2025

1 Mile

10K

View details for race Spooky Sprint - Denver

Colorado Run for the Fallen 6 Hour Run/Walk/Ruck

Palmer Lake, CO

Sunday, September 14th, 2025

View details for race Colorado Run for the Fallen 6 Hour Run/Walk/Ruck

2025 Montbello Alive! 5K

Denver, CO

Saturday, September 20th, 2025

View details for race 2025 Montbello Alive! 5K

13th Annual Superhero Event

Greeley, CO

Saturday, September 20th, 2025

10K

1 Mile

View details for race 13th Annual Superhero Event

Move Forward 5K & 10K

Denver, CO

Saturday, September 20th, 2025

10K

View details for race Move Forward 5K & 10K

Autumn Run

Buena Vista, CO

Saturday, September 20th, 2025

Half

10K

View details for race Autumn Run

Pikes Peak Ascent

Manitou Springs, CO

Saturday, September 20th, 2025

Ultra

View details for race Pikes Peak Ascent

Mountain Marmot Trail Run presented by Durango ...

Durango, CO

Saturday, September 20th, 2025

Trail

View details for race Mountain Marmot Trail Run presented by Durango Running Company

2025 ColorFest Color Run/Walk 5K

Pagosa Springs, CO

Saturday, September 20th, 2025

View details for race 2025 ColorFest Color Run/Walk 5K

Miles 4 Madison 5K & 1K

Littleton, CO

Saturday, September 20th, 2025

View details for race Miles 4 Madison 5K & 1K

Rim to Rim Royal Gorge Races: 5K Road Run, Trai...

Canon City, CO

Saturday, September 20th, 2025

Half

10K

Trail

View details for race Rim to Rim Royal Gorge Races: 5K Road Run, Trail 8 Mile, Trail Half Marathon

D 4.9 k

Peyton, CO

Saturday, September 20th, 2025

View details for race D 4.9 k

Explore more in Colorado, US

Distances:

5K 10K Half Marathon Marathon

Months:

August September October

Tags:

Trail Boston Qualifiers Fast Courses

Don't see your race? Add it!

Add Your Race (Free)