Diablo Trail Marathon
Clayton, CA, USA • September 6, 2026
Race Day Weather
61°
89° high
Breezy
Dry
Comfortable temps, big temp swing
Starting at 61°F, heat will be a factor from the gun — go out conservative and stay on top of hydration. Temps will climb significantly to 89°F by later miles, so expect fading conditions as the race progresses. Light winds shouldn't be a major factor for pacing.
Pre-raceRace windowPost-race
Mount Diablo provides spectacular views of the San Francisco Bay Area and surrounding valleys. The 4 mile course is relatively flat and fast within Mitchell Canyon. The longer events are mountainous and very scenic. Source
Historical Weather
Based on 13 years of data
Avg Temp
85°F
L:61° H:85°
RunScore
Conditions
Rain Freq
15%
2 of 13 yrs
Wind11mph
Dew48°F
Temperature History
Range of temperatures during race hours for each year.
Detailed History
| Year | Conditions | Low / High | Rain | Dew Point | Score |
|---|---|---|---|---|---|
2025 | | 64°/82° | - | 55° | |
2024 | | 60°/94° | - | 50° | |
2023 | | 58°/87° | - | 53° | |
2022 |  | 63°/72° | Light | 55° | |
2021 |  | 60°/81° | - | 54° | |
2019 | | 67°/92° | - | 57° | |
2018 | | 58°/79° | - | 51° | |
2017 | | 68°/103° | - | 54° | |
2016 | | 61°/82° | - | 52° | |
2015 |  | 65°/83° | Light | 53° | |
2014 | | 58°/82° | - | 52° | |
2013 | | 56°/81° | - | 25° | |
2012 | | 54°/82° | - | 50° |