- Weather
- 49°Ftypical startModelled estimate
- Field size
- ~400 runners
- Course
- Flat
- Elevation
- 150 ft gain · 0 ft net
Event: Full Marathon Slow Racers - Over 6 Hrs 30 Min to finish
PR9Weather9Experience6
Mid-October · Mountain West · Loop
Boise Marathon (Onward)
Boise, ID · Sunday, June 20, 2027
A flat loop along the Boise River Greenbelt, a paved multi-use path system that runs for miles through the city, one of the most extensive urban greenbelts of its kind.
Flat course along Boise River Greenbelt
- Best for PR
- Boston Qualifier
Opens the race organizer's website
Typical start
45°
Cooler than 69% of U.S. marathons
Modeled historical conditions
Elevation gain
200ft
Flatter than 54% of races
Estimated total climb
Field size
1K
Larger than 44% of races
Estimated field
PR potential
9.4/10
Top 11%
Almanac model
Percentiles compare this race against all 224 U.S. marathons in the Almanac.
Course profile
200 ft gain
Flat course, loop.
0510152026.2
Race-day weather
Modeled from location, month and coastal proximity, not verified race history.
6 AM
37°
Start
45°
Midday
56°
ExcellentGoodWarmHeat risk
Typical start sits at 45°F, excellent marathon conditions.
Typical dew point 33°F, 16% chance of precipitation, wind around 7 mph. All modeled.
The bottom line
A quietly fast race that does not ask for much beyond honest pacing.
Boise Marathon (Onward) is a strong choice for a PR attempt, and Boise offers very little meaningful elevation. The tradeoff is atmosphere: expect long quiet stretches and few spectators.
Why runners choose this race
A loop course around Boise, ID, with very little meaningful elevation change.
The case for it
- PR attempts
- Boston qualification
- Runners who want a low-key start
The tradeoffs
- No notable warnings in the data.
Course and logistics
- Course type
- Loop
- Surface
- Road
- Profile
- Flat
- Total gain
- 200 ft(estimated)
- Field size
- ~1,000 runners(estimated)
- Crowd support
- Pockets of spectators
- Entry
- Data coming soon
- Start / finish
- Start and finish in the same area
Race details
- Typical timing
- Mid-October
- Next confirmed date
- Sunday, June 20, 2027
- Region
- Mountain West
- Editorial tier
- Featured
- Data last reviewed
- 2026-08-26
- Best for PR
- Boston Qualifier
- Loop course
- Flat course
- Destination race
Similar races
Races with a comparable profile.
- Weather
- 49°Ftypical startModelled estimate
- Field size
- ~500 runners
- Course
- Flat
- Elevation
- 150 ft gain · 0 ft net
Event listed as: Marathon
PR9Weather9Experience6
- Weather
- 47°Ftypical startModelled estimate
- Field size
- ~1,000 runners
- Course
- Flat
- Elevation
- 100 ft gain
Fast coastal North Carolina qualifier
PR9Weather9Experience7