Half-Marathon races in Colorado, United States — 2026 running calendar

Heatwave Half Marathon - Denver

Littleton, Colorado, United States

Jul 11, 2026 (Sat)

Running

1.6K 5K 10K Half-Marathon +1

All-Out Dog Days

Westminster, Colorado, United States

Jul 11, 2026 (Sat)

Running

Half-Marathon 10K 5K +2

6th Annual July 4th Rock-It Run

Castle Rock, Colorado, United States

Jul 4, 2026 (Sat)

Running

5K Half-Marathon 1K

July 4th Run 5K/10K/13.1 DENVER/AURORA

Centennial, Colorado, United States

Jul 4, 2026 (Sat)

Running

5K 10K Half-Marathon 1.6K +2

Run for Chocolate 5K/10K/13.1 DENVER/AURORA

Centennial, Colorado, United States

Jul 4, 2026 (Sat)

Running

5K 10K Half-Marathon 1.6K +2

Slacker Half Marathon-Relay-4-Mile Races

Georgetown, Colorado, United States

Jun 27, 2026 (Sat)

Running

Half-Marathon 6.4K +3

Race in the Clouds - Alma Dirt Festival

Alma, Colorado, United States

Jun 25, 2026 (Thu) – Jun 27, 2027

Mountain biking, Duathlon, Trail running, Running

Ultra Marathon Half-Marathon 35.4K +16

Sloth Run 5K/10K/13.1 DENVER/AURORA

Centennial, Colorado, United States

Jun 20, 2026 (Sat) – Aug 29, 2026

$30.00 - $45.00

Running

5K 10K Half-Marathon 1.6K +8

Red, White and Brew 5k, 10k & Half Marathon

Windsor, Colorado, United States

Jun 20, 2026 (Sat)

Running

5K 10K Half-Marathon 1.6K +2

Run Juneteenth Day 5K/10K/13.1 DENVER/AURORA

Centennial, Colorado, United States

Jun 20, 2026 (Sat)

Running

5K 10K Half-Marathon 1.6K +2

All-Out Summer Breeze

Arvada, Colorado, United States

Jun 13, 2026 (Sat)

Running

Half-Marathon 10K 5K +2

The Steamboat Marathon

Steamboat Springs, Colorado, United States

Jun 7, 2026 (Sun)

Running

Marathon Half-Marathon 10K