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Traffic heat map of Sonoma County, California: 920 miles of roads shaded from blue (light) to red (heavy traffic), busiest on Redwood Highway and CA 12

Sonoma County, California Traffic Counts

Its busiest road, Redwood Highway, carries 68,461 vehicles a day, 6.4 times the average road. This page breaks down traffic in Sonoma County, California across 920 miles of monitored roads split into 23,757 segments, using multi-sourced mobile and sensor data. It goes beyond raw counts to truck flow, congestion and who is driving, so site selection and route planning rest on evidence.
Data sourced from TrafficZoom's proprietary analytics platform.
Data current as of:
Q3 2026
Updated:
September 29, 2026
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Total Traffic Volume & Performance in Sonoma County, California

Traffic

The average number of vehicles that travel each day over any road in the road network.

vehicles per day10,667
Trucks

The percentage of the total traffic volume composed of heavy vehicles.

6.5%
Average travel time

The average time of travel averaged among all vehicles traveling on the road network.

32.4 min
Congestion ratio

The rate at which the actual travel time exceeds free-flow travel time, averaged among all roads in the network.

28.9%
Drivers’ average age

Average age of residents in the geographic areas where the vehicle trips originated.

46.3 yrs
Drivers’ average income

Average income of residents in the geographic areas where the vehicle trips originated.

$109,586

The average monitored road in Sonoma County, California carries 10,667 vehicles per day. Across its 920 miles of monitored roads, that adds up to 10,645,614 vehicle-miles traveled per day (≈3.9 billion per year). Trucks are a smaller part of the mix than across California: 6.5% against 7.8%.

Busier roads than 81% of counties in California

Sonoma sees 16% lower average daily traffic volume than the state average (10,667 vehicles per day against 12,766), suggesting less demand on each road - a factor worth weighing in site selection and logistics planning. Network-wide, Sonoma accounts for about 1.1% of California's statewide total of vehicle-miles. 81% of counties in California see less traffic than Sonoma's 10,667 vehicles per day.

At 32.4 minutes, the average travel time is 6% lower than the state level. 73% of counties in California have a longer average travel time than Sonoma's 32.4 minutes.

The congestion ratio of 28.9% runs slightly higher than the state level (5% higher).

Highway vs. Non-Highway Traffic Analysis

highway traffic icon

Highway Traffic in Sonoma County, California

Trafficvehicles per day35,966
Trucks8.7%
Average travel time33.8 min
Congestion ratio62.1%
Drivers’ average age46.1 yrs
Drivers’ average income$107,520

A significant share of driving in Sonoma County, California, 43% of vehicle-miles, happens on highways. The average highway carries 35,966 vehicles per day, 255% more than the average non-highway road in the same area, which carries 10,134 vehicles per day.

Highways make up 15% of the monitored road miles (140 miles, 490 segments), so they carry more than their share: 4,607,973 vehicle-miles traveled per day (≈1.7 billion per year).

By highway travel volume, Sonoma outranks 57% of counties in California.

Lower highway truck share than 67% of counties in California

Highway truck concentration here runs 16% lower than the state average, at 8.7%. Highways here mostly serve passenger trips, so local access matters more than long-haul routing for logistics operators.

Sonoma's highway truck share (8.7%) is lower than 67% of counties in California. Sonoma's highway truck count is higher than 51% of counties in California, at roughly 3,125 trucks per day.

non-highway traffic icon

Non-highway Traffic in Sonoma County, California

Trafficvehicles per day10,134
Trucks4.9%
Average travel time32.3 min
Congestion ratio28.2%
Drivers’ average age46.4 yrs
Drivers’ average income$110,966

A little more than half of the driving in Sonoma County, California happens on local roads: 57% of all vehicle-miles. A typical local road sees 10,134 vehicles per day.

Spread over 780 miles and 23,267 segments, 85% of the road network, local roads carry a lighter load per mile: 6,037,642 vehicle-miles traveled per day (≈2.2 billion per year). The truck share on non-highway roads is 4.9%.

Drivers from higher-income areas than 75% of counties in California

Compared to highways, non-highway routes see 44% fewer trucks by share.

Non-highway congestion (28.2%) runs slightly higher than the state level (6% higher).

Sonoma's average driver income is higher than 75% of counties in California. 60% of counties in California have a younger driver population than Sonoma.

Time-of-Day & Seasonal Patterns

peak hours icon
Peak Traffic Windows
Weekday peaks:
AM peak 8:00 AM–9:00 AM and a long afternoon plateau from 3:00 PM to 8:00 PM, with volumes reaching approximately 77% higher than the daily average.
Weekend traffic:
Weekends are somewhat quieter: volumes run about 14% below weekday levels, the usual weekend dip.
seasonal traffic icon
Seasonal Fluctuation
Busy season:
June–August is the high season, with volumes +23% versus the annual average.
Lowest month:
February is the quietest month, with volumes -39% versus the annual average - the usual winter low.

Data Finding: Hourly & Seasonal Patterns

In Sonoma County, California, the peak hour concentrates about 7% of the day's traffic, and there is a strong seasonal swing of +23% in high season.

Sonoma County vs. California Traffic Comparison

Sonoma County's biggest difference from the California average is its average daily traffic per road, 16% below it. Its highway truck share is also 16% below.

MetricSonoma CountyCalifornia averageDifference
Traffic10,66712,766-16.4%
Truck % (Total Traffic)6.5%7.8%-16.0%
Truck % (Highway)8.7%10.4%-16.3%
Avg. Travel Time32.4 min34.5 min-6.2%

How Sonoma County compares

Sonoma County against nearby counties

Sonoma County tracks the 4 areas around it closely - no measure in this table sets it far apart from the areas immediately next to it, though it has the busiest roads of the five. Bigger and busier at once: more road than the areas around it and heavier traffic on it, which makes it the centre of gravity for travel in this part of the map.

Sonoma County and the 4 nearest county-level areas by centroid distance, with the California average for scale.
AreaAverage daily trafficTruck shareDaily vehicle-milesAverage travel timeCongestion ratio
Sonoma County10,6676.5%10,645,61432.4 min28.9%
Napa County, California6,4276.9%3,100,05333.9 min19.9%
Marin County, California9,8226.8%5,877,92831.2 min27.8%
Lake County, California6,1597.4%1,447,76638.4 min19.1%
Solano County, California10,2088.2%15,382,40732.4 min25.5%
California average12,7667.8%N/A34.5 min27.4%

Sonoma County ranked within California

Sonoma County sits in the top quarter of the California field on average daily traffic volume, at #12 of 58.

Sonoma County ranked among 58 county-level areas in California (1 = highest); measures without data in every county rank a smaller field, down to 52.
MeasureSonoma CountyCalifornia rank
Traffic volume (AADT)10,667#12 of 58
Highway vehicle-miles per day4,607,973#23 of 52
Truck share on highways8.7%#35 of 52
Highway trucks per day3,125#26 of 52
Average travel time32.4 min#42 of 58
Average driver income$109,586#15 of 58
Average driver age46.3 yrs#24 of 58

Busiest roads in Sonoma County, California

The three busiest roads in Sonoma County average 56,718 vehicles a day, 5.3 times the county average of 10,667 across all its monitored roads.

Redwood Highway is the busiest road, at 68,461 vehicles a day, 6,254 of them trucks (9.1%). It also carries the most trucks.

Richard "Fresh Air" Janson Bridge carries longer journeys than most roads here, with a median trip of 51.5 minutes against 32.4 county-wide.

Freight stands out on Richard "Fresh Air" Janson Bridge: trucks are 12.3% of the traffic there, against 6.5% county-wide.

Ranked by daily traffic (AADT)

Cars and light vehiclesTrucks
1Redwood HighwayMotorway · 68,461vehicles6,254trucks · 9.1%
Road class
Motorway
Congestion ratio
61.1%
Median trip time
33.7 min
Drivers’ median age
46.1 yrs
Drivers’ average income
$107,467

At 6.4 times the county average, Redwood Highway draws drivers from neighborhoods averaging $107,467 in household income.

2CA 12Motorway · 55,535vehicles2,669trucks · 4.8%
Road class
Motorway
Congestion ratio
68.7%
Median trip time
27.7 min
Drivers’ median age
46.0 yrs
Drivers’ average income
$106,824

A main artery: CA 12's busiest stretch carries 5.2 times the county average; trucks are 4.8% of it, below the county-wide 6.5%.

3CA 37Trunk road · 46,157vehicles4,395trucks · 9.5%
Road class
Trunk road
Congestion ratio
111.1%
Median trip time
50.4 min
Drivers’ median age
45.6 yrs
Drivers’ average income
$111,359

CA 37 is one of the more congested roads here: trips take 111% longer than at free-flow speed, against 29% county-wide.

4Rohnert Park ExpresswayPrimary road · 44,855vehicles1,892trucks · 4.2%
Road class
Primary road
Congestion ratio
41.4%
Median trip time
25.6 min
Drivers’ median age
42.6 yrs
Drivers’ average income
$94,905

Rohnert Park Expressway carries 4.2 times the county average at its busiest, 1,892 of them trucks (4.2%, below the county-wide 6.5%).

5Washington StreetPrimary road · 44,840vehicles1,884trucks · 4.2%
Road class
Primary road
Congestion ratio
69.1%
Median trip time
29.8 min
Drivers’ median age
50.8 yrs
Drivers’ average income
$117,041

Washington Street carries 4.2 times the county average on its busiest stretch, where the median trip lasts 29.8 minutes.

Ranked by trucks per day

Cars and light vehiclesTrucks
1Redwood HighwayMotorway · #1 by traffic68,461vehicles6,254trucks · 9.1%
2Richard "Fresh Air" Janson BridgeTrunk road · 40,117vehicles4,936trucks · 12.3%
Road class
Trunk road
Congestion ratio
95.5%
Median trip time
51.5 min
Drivers’ median age
45.8 yrs
Drivers’ average income
$112,685

Delays build on Richard "Fresh Air" Janson Bridge: its congestion ratio of 96% over free-flow time is well above the county's 29%.

3CA 37Trunk road · #3 by traffic46,157vehicles4,395trucks · 9.5%
4Sears Point RoadTrunk road · 39,182vehicles3,606trucks · 9.2%
Road class
Trunk road
Congestion ratio
57.5%
Median trip time
50.3 min
Drivers’ median age
47.2 yrs
Drivers’ average income
$112,776

Drivers on Sears Point Road are on long journeys, a median 50.3 minutes against 32.4 county-wide: a through route more than a local street.

5CA 12Motorway · #2 by traffic55,535vehicles2,669trucks · 4.8%
How to read these road counts
  • The first number is AADT, annual average daily traffic: the vehicles passing a point on an average day, both directions combined and trucks included. On a divided highway both carriageways are added together.
  • Traffic changes along a road, with more near interchanges and towns and less in open country. Every figure for a road describes its busiest stretch in the county, so the two rankings show the same numbers for the same road.
  • The second number is the trucks on that stretch, a part of its AADT. The bar splits the AADT into cars and light vehicles (blue) and trucks (amber).
  • See segment-level AADT for any road on TrafficZoom.

Data Sources & Methodology

The data presented on this page is derived from TrafficZoom's proprietary analytics platform, which aggregates and normalizes information from multiple sources, including:

Mobile device location data (anonymized and aggregated)

Road sensor networks and traffic counters

Historical traffic pattern databases

Public traffic count programs published by the

SonomaDepartment of Transportation

Demographic Baseline for O-D Modeling

U.S. Census Bureau
All metrics represent estimates based on statistical modeling and are intended for strategic planning purposes.
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Data current as of:
Q3 2026

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Counties near Sonoma County

The same traffic breakdown for the areas closest to Sonoma County, California.

Need segment-level traffic data?

Identify traffic patterns street by street and analyze the exact corridors that matter to your project.