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Triathlon Calendar near O'Fallon 2025-2026

Explore the top triathlons near O'Fallon for 2025-2026! We've gathered 57 exciting races in the area. Check out our detailed list below to find your next local race.

March 2026
Mar
15
Sunday

Florissant St. Patrick's Day 5K Run

5 km
Mar
21
Saturday

American Bottoms 100

55 mi 110 mi
Mar
21
Saturday

Go Green St. Paddy's Day Run

5 km
Mar
22
Sunday

Bodies Race Company - St. Louis

5 km 10 km Half Marathon
Mar
28
Saturday

Double Chubb 50K

Trail Run 8 mi 25 km 50 km
Mar
28
Saturday

Schon Park 9 Endurance Run

Backyard Ultra 3 hr 6 hr 9 hr
April 2026
Apr
4
Saturday

GO! St. Louis Marathon

5 km
Apr
11
Saturday

Greater St. Louis Marathon

5 km 10 km Half Marathon Marathon
Apr
11
Saturday

Kids & Cops Doughnut Run 5K

5 km
Apr
18
Saturday

DoNot Stop Half Marathon - St. Louis

5 km 10 km Half Marathon
Apr
19
Sunday

Beat Beethoven 5K - St. Louis

5 km
May 2026
May
16
Saturday

Bodies Race Company - St. Louis

5 km 10 km Half Marathon
June 2026
Jun
28
Sunday

St. Louis Triathlon

Triathlon
August 2026
Aug
8
Saturday

Drink MO Beer 10k

5 km 10 km
Aug
8
Saturday

Swifty Fun Run - St. Louis

5 km 10 km 13 mi
Aug
15
Saturday

Feed My Sheep Ministry

5 km
Aug
29
Saturday

The Labor Day Slay

Trail Run 5 km 10 km Half Marathon
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