Runners will face temperatures starting at 64°F and climbing to 82°F, with average humidity at a comfortable 29%. Winds will be light from the S, reaching up to 9 mph. As temperatures rise, it's crucial for runners to pace conservatively and stay hydrated throughout the race.

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Pace Calculator

Distance: 26.2mi

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Race Info

Named among the Best Fall Marathons by Runner's World, #5 Best Half Marathon in the US by Active, as well as #1 Best in Colorado and one of the "Most Beautiful Marathons in the World" by HalfMarathons.Net, Boulderthon drew over 6,000 runners from all 50 states and 18 countries in 2023, and has doubled in size every year since its inception. Source

Website

Race weekend

Sunday, September 27

7:00 AMMarathon (26.2 mi)

7:00 AMHalf Marathon (13.1 mi)

7:45 AM5K (3.1 mi)

8:10 AM10K (6.2 mi)

Course Map

FAQ

When is the 2026 Boulderthon Marathon?

The 2026 Boulderthon Marathon will be held on Sunday September 27, 2026.

Is the Boulderthon Marathon a Boston Marathon Qualifier?

Yes, the Boulderthon Marathon is an official Boston Marathon qualifier.

What is the time limit for the Boulderthon Marathon?

The time limit for the Boulderthon Marathon is 6 hours.

What will the weather be like for the 2026 Boulderthon Marathon?

The forecast calls for a high of 84°F and a low of 59°F with a 0% chance of rain.

Historical Weather

Based on 5 years of data

Avg Temp

56°F

L:47° H:67°

RunScore

Conditions

Rain Freq

0 of 5 yrs

Wind1mph

Dew36°F

Temperature History

Range of temperatures during race hours for each year.

Detailed History

Year	Low / High	Rain	Dew Point
2025 Boulderthon Marathon Partly cloudy throughout the day. 2025	52°/68°	-	45°
2024 Boulderthon Marathon Clear conditions throughout the day. 2024	57°/75°	-	40°
2023 Boulderthon Marathon Clear conditions throughout the day. 2023	44°/70°	-	32°
2022 Boulderthon Marathon Clear conditions throughout the day. 2022	41°/63°	-	35°
2021 Boulderthon Marathon Clear conditions throughout the day. 2021	42°/59°	-	29°

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Free guidesMarathon Fueling Guide·Carb Loading Guide·Race Morning Guide·Race Day Gear Guide·Pacing Strategy Guide·Mental Strategy Guide