Starting at 60°F, heat will be a factor from the gun — go out conservative and stay on top of hydration. Temps will climb significantly to 79°F by later miles, so expect fading conditions as the race progresses. Light winds shouldn't be a major factor for pacing.

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Distance: 6.2mi

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Race Info

The 10K is a single run of the Boulder Reservoir loop, held on the Saturday of race weekend. It starts and finishes by the reservoir parking lot on Reservoir Road, crosses the dam and turns back on 63rd Street before returning along Monarch Road, 55th Street and 51st Street. Most of the course is dirt road and trail, and it is flat with views across the water to the Rocky Mountains.

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Race weekend

Saturday, August 15

7:15 AMMarathon (26.2 mi)7:20 AM3/4 Marathon (19.7 mi)7:25 AMHalf Marathon (13.1 mi)

7:30 AM10K (6.2 mi)

Course Map

FAQ

When is the 2026 Boulder Rez 10K?

The 2026 Boulder Rez 10K will be held on Saturday August 15, 2026.

What is the time limit for the Boulder Rez 10K?

The time limit for the Boulder Rez 10K is 6.5 hours.

What will the weather be like for the 2026 Boulder Rez 10K?

The forecast calls for a high of 79°F and a low of 59°F with a 100% chance of rain. Check our detailed hourly forecast above for the best 10K race plan.

Historical Weather

Based on 10 years of data

Avg Temp

56°F

L:54° H:58°

RunScore

Conditions

Rain Freq

0 of 10 yrs

Wind2mph

Dew47°F

Temperature History

Range of temperatures during race hours for each year.

Detailed History

Year	Low / High	Rain	Dew Point
2026 Boulder Rez 10K Becoming cloudy in the afternoon with late afternoon rain. 2026	60°/66°	-	59°
2025 Boulder Rez 10K Clear conditions throughout the day with late afternoon rain. 2025	54°/61°	-	51°
2024 Boulder Rez 10K Clear conditions throughout the day. 2024	63°/70°	-	45°
2023 Boulder Rez 10K Partly cloudy throughout the day. 2023	64°/65°	-	51°
2022 Boulder Rez 10K Partly cloudy throughout the day with late afternoon rain. 2022	67°/72°	-	53°
2021 Boulder Rez 10K Clear conditions throughout the day. 2021	61°/66°	-	55°
2019 Boulder Rez 10K Partly cloudy throughout the day with late afternoon rain. 2019	54°/59°	-	47°
2018 Boulder Rez 10K Partly cloudy throughout the day with late afternoon rain. 2018	38°/40°	-	36°
2017 Boulder Rez 10K Clear conditions throughout the day. 2017	29°/30°	-	28°
2015 Boulder Rez 10K Cloudy skies throughout the day. 2015	47°/49°	-	48°

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