Diamond Mountain Road Climb from Saint Helena Highway
- long (5.4 km)
- 3.3 mi
- long (5.4 km)
- of climbing (440 m)
- 1,444 ft
- of climbing (440 m)
- average grade
- 8.2%
- average grade
- steepest 500 m
- 13.4%
- steepest 500 m
Elevation profile
From 341 ft at the bottom to 1,785 ft at the top. Grades are averaged over each half kilometre, from USGS elevation data, so short ramps can be steeper than they show.
Weather at the top of Diamond Mountain Road this week
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Is it safe to bike up Diamond Mountain Road?
We don't rate roads as safe or unsafe: crash counts can't say how risky a ride is, and roads people like to ride draw more riders, so they see more crashes. What the records show: no bike crashes were reported along the climb from 2021–2025.
Common questions about Diamond Mountain Road
- How long and steep is the Diamond Mountain Road from Saint Helena Highway climb?
- 3.3 miles (5.4 km) at 8.2% on average, climbing 1,444 ft (440 m) from 341 ft to 1,785 ft. The steepest half kilometre averages 13.4%. That makes it a Category 2 climb.
- Where does the climb start and finish?
- It starts at 38.56643, -122.56367, where Diamond Mountain Road leaves Saint Helena Highway, and ends where the road ends at 38.54729, -122.58169.
- Is Diamond Mountain Road paved?
- Yes, by its OpenStreetMap tags.
- How is the category worked out?
- From the climb's shape only: length in metres × average grade (%) of 16,000 or more for Cat 3, 32,000 for Cat 2, 64,000 for Cat 1 and 80,000 for HC. It describes how hard the climb is, not traffic or crashes.
- Where does this data come from?
- The climb is found from OpenStreetMap roads and USGS 3DEP elevation (every climb, not a list of famous ones). Access is from OpenStreetMap tags; gates and closures change, so obey posted signs. Crash counts are police reports in the California Crash Reporting System (CCRS) on data.ca.gov, counted where their map location is within 100 ft of the climb. The forecast is from the National Weather Service.
Other climbs nearby
- Kortum Canyon RoadCat 3 · 2.2 mi at 7.2% · 827 ft · starts 1.1 mi away
- Lake County HighwayCat 2 · 7.5 mi at 4.8% · 1,896 ft · starts 1.7 mi away
- Petrified Forest RoadCat 3 · 2.0 mi at 7.2% · 764 ft · starts 2.1 mi away
- Old Lawley Toll RoadCat 2 · 3.1 mi at 6.5% · 1,073 ft · starts 3.2 mi away
- Fechter RoadCat 3 · 1.1 mi at 11.5% · 636 ft · starts 3.4 mi away
- Langtry RoadCat 3 · 2.1 mi at 5.4% · 597 ft · starts 3.9 mi away
- Mattei RoadCat 3 · 1.1 mi at 9.8% · 564 ft · starts 4.3 mi away
- Deer Park RoadCat 2 · 4.2 mi at 5.2% · 1,155 ft · starts 5.3 mi away
Found from OpenStreetMap roads and USGS 3DEP elevation; ranked on shape only. Category 2: length in metres × average grade (%) of 16,000 or more for Cat 3, 32,000 for Cat 2, 64,000 for Cat 1 and 80,000 for HC. It describes how hard the climb is, not traffic or crashes. Crashes: bike crashes reported within 100 ft of the climb, 2021–2025, from the California Crash Reporting System (CCRS), counted only where the report has map coordinates. Weather: National Weather Service. Access from OpenStreetMap tags; obey posted signs. How the data works.