Boulderthon Marathon

Boulder, CO, USA · September 27, 2026
partly-cloudy-day51°·74° high·Light·Dry
9
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Race Day Weather

partly-cloudy-day
51°at start
77° high
Light
Dry

Cool start, warming trend ahead

Runners will face a cool start at 51°F, gradually warming to 76°F by race end. Winds from the S at 7 mph will remain mild, with gusts up to 16 mph. With average humidity at 37%, runners should maintain hydration and consider pacing conservatively as temperatures rise.

Race day forecast available in 46 days
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Pace Calculator

Distance: 26.2mi
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

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Course Map Unavailable

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FAQ

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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 79°F and a low of 50°F with a 4% chance of rain.

Historical Weather

Based on 5 years of data
Avg Temp
75°F
L:50° H:75°
RunScore
8
Conditions
Rain Freq
0%
0 of 5 yrs
Wind4mph
Dew35°F

Temperature History

Range of temperatures during race hours for each year.

Detailed History

YearConditionsLow / HighRainScoreResults

2025 Boulderthon Marathon

Partly cloudy throughout the day.

2025
clear-day
54°/77°-
8

2024 Boulderthon Marathon

Clear conditions throughout the day.

2024
clear-day
60°/84°-
8

2023 Boulderthon Marathon

Clear conditions throughout the day.

2023
clear-day
46°/77°-
8

2022 Boulderthon Marathon

Clear conditions throughout the day.

2022
clear-day
43°/72°-
8

2021 Boulderthon Marathon

Clear conditions throughout the day.

2021
clear-day
45°/66°-
8

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