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 conditions ahead

Runners will face a temperature rise from 51°F at the start to a warm 76°F by race end. With light winds from the S, humidity remains low at 37% and dew point at 38°F. Runners should start conservatively, adjusting their pace as temperatures climb to avoid overheating.

Race day forecast available in 7 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 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
72°F
L:47° H:72°
RunScore
8
Conditions
Rain Freq
0%
0 of 5 yrs
Wind3mph
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
52°/74°-
8

2024 Boulderthon Marathon

Clear conditions throughout the day.

2024
clear-day
57°/80°-
8

2023 Boulderthon Marathon

Clear conditions throughout the day.

2023
clear-night
44°/75°-
8

2022 Boulderthon Marathon

Clear conditions throughout the day.

2022
clear-night
41°/69°-
8

2021 Boulderthon Marathon

Clear conditions throughout the day.

2021
clear-night
42°/63°-
8

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