Boulderthon Marathon

Boulder, CO, USA · September 27, 2026

52°·74° high·Light·Dry

Weather

Pace Calc

Race Day Weather

52°at start

75° high

Light

Dry

Warming trend, light winds

Runners will face a temperature rise from 52°F at the start to 75°F by the finish, with average humidity at 40% and a dew point of 37°F. Winds will be light, coming from the ESE at 5 mph. Given the heat increase, pacing adjustments and hydration strategies should be prioritized as the race progresses.

Race day forecast available in 146 days

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Distance: 26.2mi

Target Finish Time

0:00:00

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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

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 6.5 hours.

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

The forecast calls for a high of 75°F and a low of 51°F with a 0% chance of rain.

Historical Weather

Based on 5 years of data

Avg Temp

75°F

L:50° H:75°

RunScore

Conditions

Rain Freq

0 of 5 yrs

Wind4mph

Dew35°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	54°/77°	-	46°
2024 Boulderthon Marathon Clear conditions throughout the day. 2024	60°/84°	-	41°
2023 Boulderthon Marathon Clear conditions throughout the day. 2023	46°/77°	-	30°
2022 Boulderthon Marathon Clear conditions throughout the day. 2022	43°/72°	-	34°
2021 Boulderthon Marathon Clear conditions throughout the day. 2021	45°/66°	-	29°

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