Boulderthon - Boulder Marathon
Boulder, United States of America · Sunday 27 September 2026
The event is a marathon held in Boulder, Colorado, typically scheduled for late September. The course starts by traversing back roads near the foothills of the Flatirons mountain range, then continues into Downtown Boulder, finishing on the pedestrian Pearl Street Mall. The route is described as a loop, run entirely on paved roads.
Difficulty Calculator
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:m
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Adjusted Time
4:10:34
Time difference: +10.6 minutes compared to a flat, road, temperate course.
Course Details
Elevation Gain255m
Elevation High1648m
Elevation Low1557m
Weather Forecast
High26°C
Low12°C
Chance of Rain12%
How hard is Boulderthon - Boulder Marathon?
Difficultharder than 70% of marathons
Flattest / easiestHardest
On our difficulty model, Boulderthon - Boulder Marathon plays about 12 minutes slower than an average road marathon for a 3:30 runner. It ranks #350 hardest of 1150 marathons we analyse, and #180 of 575 in United States of America. Use the calculator above to see the exact adjusted time for your own goal pace.
What will you run at Boulderthon - Boulder Marathon?
Estimated finish times on this course versus the same effort on an average road marathon, based on its elevation, surface, and expected race-day temperature.
| Average-course time | On Boulderthon - Boulder Marathon | Difference |
|---|---|---|
| 3:00:00 | 3:04:20 | +04:20 |
| 3:30:00 | 3:37:19 | +07:19 |
| 4:00:00 | 4:10:34 | +10:34 |
| 4:30:00 | 4:44:06 | +14:06 |
| 5:00:00 | 5:17:52 | +17:52 |
| 5:30:00 | 5:51:52 | +21:52 |
| 6:00:00 | 6:26:05 | +26:05 |
Use the calculator above for your exact goal time. Want a prediction from your own training? Try the marathon time predictor.
Boulderthon - Boulder Marathon 2026 Course Analysis
Boulderthon - Boulder Marathon is a full marathon held in Boulder, United States of America. It is scheduled for Sunday 27 September 2026. The course is run on road surface with 255m of total climbing, with its high point near 1648m above sea level. For registration and full race details, visit the official Boulderthon - Boulder Marathon website.
Elevation Profile
With 255m of total climbing, this is a gently undulating course. The elevation changes are manageable for most runners and shouldn't greatly affect your pacing.
Expected Race Day Weather
Based on historical weather data for September, the expected race day conditions are as follows. Moderate temperatures between 12°C and 26°C are expected. While comfortable for most runners, those targeting fast times should pay attention to hydration, as these temperatures can impact performance on race day. There is a low chance of rain (12%), so dry conditions are likely.
Surface Type: Road
Boulderthon - Boulder Marathon is run on road surfaces, which provide the fastest and most predictable conditions for racing. Road courses allow for consistent pacing and are typically the best choice for a personal best.
Looking for an easier marathon or a tougher challenge? You can also compare Boulderthon - Boulder Marathon against other marathons to find the right race for your goals.
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If Boulderthon - Boulder Marathon fits your goal, these courses play out about the same on our difficulty model.
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