Boulderthon Marathon

Boulder, CO, USA • September 28, 2025
TopDescriptionCourseCommunity
Register

Subscribe

Get updates on the Boulderthon Marathon race forecast and be the first to know if the forecast shifts.

Text Updates

Maximum one update per day. Standard messaging rates apply. Currently only supports USA, UK, and Canada.

Phone Number

Email Updates

By submitting your email you agree to receive weather forecasts and racecast.io updates.

partly-cloudy-day Partly cloudy throughout the day.

Training Metrics and Recovery Insights, Beautiful AMOLED Display. Garmin Forerunner 265.When you buy through our links, we may earn a commission.

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

Area Map

Course Maps

FAQ

Ask a Question about the Boulderthon Marathon

Racecast Concierge (free during beta)

Ask a question about the Boulderthon Marathon and we'll do the hard part and find the answer for you within 48 hours.

By using Racecast Concierge, you agree to receive email alerts pertaining to the Boulderthon Marathon and general racecast.io updates.

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.

Community

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

Historical Weather

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