43 Upcoming Races Near Boulder, CO in September, 2026

Diplo's Run Club Denver

Denver, CO

Sunday, July 12th, 2026

Featured

Code:FTR10

View details for race Diplo's Run Club Denver

Demon Dash

Arvada, CO

Saturday, September 5th, 2026

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Golden Harvest Half Marathon & 5k/10k - Denver

Westminster, CO

Saturday, September 5th, 2026

1 Mile

10K

View details for race Golden Harvest Half Marathon & 5k/10k - Denver

Cirque Series - Arapahoe Basin, CO

Keystone, CO

Saturday, September 5th, 2026

Trail

View details for race Cirque Series - Arapahoe Basin, CO

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Golden Harvest Half Marathon & 5k/10k - Denver

Denver, CO

Saturday, September 5th, 2026

1 Mile

10K

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Raising the Barr

Brighton, CO

Saturday, September 5th, 2026

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Labor Day Half Marathon

Parker, CO

Monday, September 7th, 2026

Half

10K

Fast

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FCA All Abilities Labor Day 5K

Loveland, CO

Monday, September 7th, 2026

View details for race FCA All Abilities Labor Day 5K

FCA All-Abilities Labor Day 5K

Loveland, CO

Monday, September 7th, 2026

1 Mile

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14th Annual Superhero Event

Greeley, CO

Thursday, September 10th, 2026

10K

1 Mile

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The Denver 5k

Denver, CO

Saturday, September 12th, 2026

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Black Squirrel Half Marathon

Bellvue, CO

Saturday, September 12th, 2026

Half

Trail

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For The City Network 5K

Greeley, CO

Saturday, September 12th, 2026

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6 Dot Dash

Littleton, CO

Saturday, September 12th, 2026

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Jungle Dash

Loveland, CO

Saturday, September 12th, 2026

1 Mile

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Healthy Kids Running Series Fall 2026 - Denver, CO

Denver, CO

Sunday, September 13th, 2026

View details for race Healthy Kids Running Series Fall 2026 - Denver, CO

Buffalo Bicycle Classic

Boulder, CO

Sunday, September 13th, 2026

Ultra

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Honey Bee Hustle

Loveland, CO

Sunday, September 13th, 2026

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Tiger Prowl 5K

Denver, CO

Sunday, September 13th, 2026

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RMRR Fall Marathon Training Series #2

Thornton, CO

Sunday, September 13th, 2026

Ultra

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9/11 Heroes Run - Denver, Colorado

Denver, CO

Sunday, September 13th, 2026

1 Mile

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

RMRR September Trophy Series

Thornton, CO

Sunday, September 13th, 2026

10K

Fast

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Severance Glow 5K Run or Walk

Severance, CO

Friday, September 18th, 2026

Trail

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Denver: Walk With Autism and Resource Fair

Denver, CO

Saturday, September 19th, 2026

View details for race Denver: Walk With Autism and Resource Fair

Wellington STAR Foundation 5K 10K

Wellington, CO

Saturday, September 19th, 2026

10K

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All-Out Fall Fest

Westminster, CO

Saturday, September 19th, 2026

Half

10K

Trail

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Miles 4 Madison 5K & 1K

Littleton, CO

Saturday, September 19th, 2026

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

Gummball 5K

Brighton, CO

Saturday, September 19th, 2026

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20th Annual Golden Gallop

Golden, CO

Sunday, September 20th, 2026

10K

Trail

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Farmers 5000

Wheat Ridge, CO

Sunday, September 20th, 2026

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Expo Park XC Runs

Aurora, CO

Sunday, September 20th, 2026

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Fall Equinox

Fort Collins, CO

Sunday, September 20th, 2026

Half

Fast

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CG Adventure Club - Elevation Everest

Winter Park, CO

Wednesday, September 23rd, 2026

Trail

View details for race CG Adventure Club - Elevation Everest

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

Parker, CO

Saturday, September 26th, 2026

10K

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

Lisa Nelson’s Mustang Stampede 5K

Arvada, CO

Saturday, September 26th, 2026

View details for race Lisa Nelson’s Mustang Stampede 5K

Runway 5K - Run for the Angels

Broomfield, CO

Saturday, September 26th, 2026

View details for race Runway 5K - Run for the Angels

NIGHT NATION RUN - DENVER

Commerce City, CO

Saturday, September 26th, 2026

View details for race NIGHT NATION RUN - DENVER

Estes Epic

Estes Park, CO

Saturday, September 26th, 2026

Ultra

Trail

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HRCA Oktoberfest 5K

Littleton, CO

Saturday, September 26th, 2026

View details for race HRCA Oktoberfest 5K

Race to the Shield Homecoming Run

Bethoud, CO

Saturday, September 26th, 2026

View details for race Race to the Shield Homecoming Run

Joy & Justice 5k

Timnath, CO

Sunday, September 27th, 2026

1 Mile

View details for race Joy & Justice 5k

RMRR Fall Marathon Training Series #3

Thornton, CO

Sunday, September 27th, 2026

10 Miles

Ultra

View details for race RMRR Fall Marathon Training Series #3

Colorado Coyotes Youth XC Invitational

Cenennial, CO

Sunday, September 27th, 2026

View details for race Colorado Coyotes Youth XC Invitational

Running for Children's Rights to Both Parents -...

Boulder, CO

Sunday, September 27th, 2026

Half

10K

View details for race Running for Children's Rights to Both Parents - 9 of 50 Half Marathons in 50 States

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