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Triathlon Calendar near O'Fallon 2025-2026

Explore the top triathlons near O'Fallon for 2025-2026! We've gathered 34 exciting races in the area. Check out our detailed list below to find your next local race.

October 2025
Oct
18
Saturday

Minnie Ha Ha 12 Hour Run

Backyard Ultra 6 hr 12 hr
Oct
24
Friday

Moonlight Howl 5K

5 km
Oct
25
Saturday

The Innsbrook Half Marathon

10 km 13 mi
Oct
25
Saturday

Babler Bongo 15K Trail Race

Trail Run 15 km
Oct
25
Saturday

Hot Cider Hustle - St. Louis

5 km 10 km
November 2025
Nov
9
Sunday

Saint Louis Half Marathon

5 km 13 mi
Nov
27
Thursday

WILDWOOD Turkey Trot 10K

5 km 10 km
Nov
27
Thursday

St. Louis Turkey Trot 8K

5 km 8 km
December 2025
Dec
6
Saturday

Wild in the Woods - 5 & 10 Mile Trail Race

Trail Run 5 mi 10 mi
January 2026
Jan
17-18
Sa - Su

The Shippey Endurance Runs

Trail Run 20 mi 40 mi 100 km 100 mi
February 2026
Feb
7
Saturday

Castlewood Cup

Trail Run 15 km
Feb
28
Saturday

Shrewsbury Thrifty Fifty

1 hr 50 km 50 mi
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