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Half Marathon Calendar near Thornton 2025-2026

Explore the top half marathons near Thornton for 2025-2026! We've gathered 47 exciting races in the area. Check out our detailed list below to find your next local race.

March 2026
Mar
14
Saturday

The Best Races - Centennial

5 km 10 km 13 mi
Mar
22
Sunday

All-Out Spring Fever

5 km 10 km Half Marathon
April 2026
Apr
4
Saturday

The Best Races - Centennial

5 km 10 km 13 mi
Apr
11
Saturday

Boulder Rez Half

5 km 10 km Half Marathon
Apr
12
Sunday

Platte River Half-Marathon

Half Marathon
Apr
12
Sunday

Spring Fling Prairie Dog Half Marathon

5 km 10 km 13 mi
Apr
18
Saturday

All-Out Beat the Heat

5 km 10 km Half Marathon
Apr
18
Saturday

Mountain Ridge Trail Race

Trail Run 5 km 10 km 13 mi 22 mi
Apr
25
Saturday

Runs With Scissors Races

Half Marathon Marathon 50 km
Apr
25
Saturday

The Best Races - Centennial

5 km 10 km 13 mi
May 2026
May
2
Saturday

The Best Races - Centennial

5 km 10 km 13 mi
May
3
Sunday

Longmont Half

5 km Half Marathon
May
15-17
Fr - Su

Denver Colfax Marathon

10 mi 13 mi 26 mi
May
23
Saturday

The Best Races - Centennial

5 km 10 km 13 mi
June 2026
Jun
7
Sunday

Colorado 13er Half Marathon

5 km 10 km 13 mi
Jun
13
Saturday

All-Out Summer Breeze

5 km 10 km Half Marathon
Jun
13
Saturday

Barr Lake Trail Race

Trail Run 3 mi 9 mi ... 18 mi 32 mi
Jun
20
Saturday

The Best Races - Centennial

5 km 10 km 13 mi
July 2026
Jul
4
Saturday

The Best Races - Centennial

5 km 10 km 13 mi
Jul
11
Saturday

All-Out Dog Days

5 km 10 km Half Marathon
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