Boulderthon - Boulder Marathon
Boulder, United States of America · Monday 27 September 2027
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
h
:m
:s
Adjusted Time
4:15:30
Time difference: +15.5 minutes compared to a flat, road, temperate course.
Course Details
Elevation Gain255m
Elevation High1648m
Elevation Low1557m
Weather Forecast
High29°C
Low16°C
Chance of Rain13%
How hard is Boulderthon - Boulder Marathon?
Very Difficultharder than 72% of marathons
Flattest / easiestHardest
On our difficulty model, Boulderthon - Boulder Marathon plays about 16 minutes slower than an average road marathon for a 3:30 runner. It ranks #324 hardest of 1151 marathons we analyse, and #178 of 576 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 | 3:07:32 | +07:32 |
| 3:30:00 | 3:41:21 | +11:21 |
| 4:00:00 | 4:15:30 | +15:30 |
| 4:30:00 | 4:49:59 | +19:59 |
| 5:00:00 | 5:24:45 | +24:45 |
| 5:30:00 | 5:59:49 | +29:49 |
| 6:00:00 | 6:35:09 | +35:09 |
Use the calculator above for your exact goal time. Want a prediction from your own training? Try the marathon time predictor.
Boulderthon - Boulder Marathon 2027 Course Analysis
Boulderthon - Boulder Marathon is a full marathon held in Boulder, United States of America. It is scheduled for Monday 27 September 2027. 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. Hot conditions are expected, with temperatures between 16°C and 29°C. Heat is one of the biggest performance factors in distance running - for every degree above 15°C, finish times can slow by roughly 1-2%. Extra hydration and a conservative start are strongly recommended. There is a low chance of rain (13%), 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.
Marathons of similar difficulty
If Boulderthon - Boulder Marathon fits your goal, these courses play out about the same on our difficulty model.
Other Marathons in United States of America
Holloman Ace of Races Marathon
Alamogordo, United States of America
Road104m gainOct 2026
Des Plaines River Trail Marathon
Libertyville, United States of America
Trail144m gainOct 2026
Hartford Marathon
Hartford, United States of America
Trail230m gainOct 2026
Rogue Marathon
Medford, United States of America
Road168m gainOct 2026
Whiskey Row Marathon
Prescott, United States of America
Road0m gainOct 2026
Freedom's Run Marathon
Harpers Ferry National Park, United States of America
Road0m gainOct 2026