Boulderthon Marathon

Boulder, CO, USA • September 28, 2025
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partly-cloudy-day Partly cloudy throughout the day.

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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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When is the 2025 Boulderthon Marathon?

The 2025 Boulderthon Marathon will be held on Sunday September 28, 2025.

Is the Boulderthon Marathon a Boston Marathon Qualfier?

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.

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Historical Weather & Results

RunScore
Run Score: 8
Temp
75°F
Min/Max
49°/75°F
Dew
32°F
Days of Rain
0/4
Wind
4mph
Tap a row for details.
YearLow / HighRainResults

Boulderthon Marathon 2024 Weather History

Clear conditions throughout the day.

2024
clear-day
60°/ 84°-
Run Score: 8

Boulderthon Marathon 2023 Weather History

Clear conditions throughout the day.

2023
clear-day
46°/ 77°-
Run Score: 8

Boulderthon Marathon 2022 Weather History

Clear conditions throughout the day.

2022
clear-day
43°/ 72°-
Run Score: 8

Boulderthon Marathon 2021 Weather History

Clear conditions throughout the day.

2021
clear-day
45°/ 66°-
Run Score: 8
You Need an Account For That

Setting up a racecast.io account will allow you to start building a reputation in the community. Over time you'll be able to rate races, join the discussion, and post in the community.

Right now we are invite only, you can get on the waitlist by entering your email below:

OR
You Need an Account For That

Setting up a racecast.io account will allow you to start building a reputation in the community. Over time you'll be able to rate races, join the discussion, and post in the community.

Right now we are invite only, you can get on the waitlist by entering your email below:

OR