Twin Sisters Road Climb
- long (3.3 km)
- 2.0 mi
- long (3.3 km)
- of climbing (287 m)
- 942 ft
- of climbing (287 m)
- average grade
- 8.8%
- average grade
- steepest 500 m
- 11.2%
- steepest 500 m
Elevation profile
From 164 ft at the bottom to 1,106 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 Twin Sisters Road this week
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Is it safe to bike up Twin Sisters 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. The records here are also incomplete: most reports along it are filed under Napa, where only 57% of reported bike crashes have a map location, so the numbers here are too low. What the records show: no bike crashes were reported along the climb from 2021–2025.
Common questions about Twin Sisters Road
- How long and steep is the Twin Sisters Road climb?
- 2.0 miles (3.3 km) at 8.8% on average, climbing 942 ft (287 m) from 164 ft to 1,106 ft. The steepest half kilometre averages 11.2%. That makes it a Category 3 climb.
- Where does the climb start and finish?
- It starts at 38.29891, -122.1272, where Twin Sisters Road leaves Suisun Valley Road, and ends at a gate at 38.30138, -122.15348.
- Is Twin Sisters 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
- Hidden Springs RoadCat 3 · 1.1 mi at 12.3% · 682 ft · starts 2.4 mi away
- Grandview DriveCat 3 · 1.3 mi at 10.5% · 732 ft · starts 2.9 mi away
- Green Valley Road from Wild Horse Valley RoadCat 3 · 2.0 mi at 7.1% · 755 ft · starts 5.4 mi away
- Wild Horse Valley RoadCat 2 · 2.8 mi at 8.7% · 1,283 ft · starts 5.9 mi away
- Monticello Road from Wooden Valley RoadCat 3 · 2.0 mi at 5.1% · 538 ft · starts 6.7 mi away
- Polson RoadCat 3 · 2.0 mi at 7% · 741 ft · starts 7.5 mi away
- Gates Canyon RoadCat 1 · 6.9 mi at 6.7% · 2,454 ft · starts 7.7 mi away
- Atlas Peak RoadCat 2 · 9.9 mi at 3.9% · 2,060 ft · starts 8.0 mi away
Bike crash hotspots nearby
Found from OpenStreetMap roads and USGS 3DEP elevation; ranked on shape only. Category 3: 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.