This 478.7-mile drive from Thornton, CA to San Diego, CA will take approximately 8 hours and 57 minutes, making it a solid two-day trip rather than a single-day push. Your journey will primarily follow the Westside Freeway and the I 5 Truck before merging onto the San Diego Freeway, with 99% of the route being highway driving. The estimated fuel cost for this trip is around $110. You'll experience a highway-focused profile for the entirety of your travel, so plan for consistent speeds and limited opportunities for spontaneous scenic detours. With two recommended stops and a longest uninterrupted stretch of 271.8 miles on the Westside Freeway, breaking up this Pacific Coast to Pacific Coast drive is key to a comfortable experience.
Trip Pace
Best split across 2 days
Treat the return leg as its own travel day rather than an afterthought.
Break Rhythm
2 planned breaks
Plan on a short reset every 3 to 4 hours to stay fresh behind the wheel.
Midpoint
239.3 miles from Thornton, CA
A natural place for your longest stop of the day
, about 4h 18m into the drive
.
Main Roads
Road
Distance
Duration
Westside Freeway
271.8 mi
4h 52m
I 5 Truck
83.3 mi
1h 36m
San Diego Freeway
76.5 mi
1h 29m
Santa Ana Freeway
35 mi
40m
Golden State Freeway
5.3 mi
6m
Walnut Avenue
2.2 mi
4m
Front Street
0.5 mi
1m
Jamboree Road
0.5 mi
<1m
Longest stretch:
Westside Freeway
— 271.8 mi, about 4h 52m
Turn-by-Turn Driving Directions
Step-by-step road directions between Thornton, CA and San Diego, CA.
1
Start on J8
0.2 mi·20 sec·Thornton Road
2
Turn straight onto J11
0.2 mi·28 sec·West Walnut Grove Road
3
Take the ramp
0.3 mi·41 sec
4
Merge onto I 5
34 mi·37 min·Westside Freeway
Use the straight / slight right lanes.
5
Keep slight left at fork onto I 5
0.8 mi·48 sec·Westside Freeway
6
Keep slight left at fork onto I 5
237 mi·4 hr 13 min·Westside Freeway
Use the straight / slight right lanes.
7
Keep slight right at fork onto I 5 Truck
58 mi·1 hr 6 min·I 5 Truck
Use the straight / slight right lanes.
8
Keep slight left at fork onto I 5
4.1 mi·4 min·Golden State Freeway
Use the straight / slight right lanes.
9
Keep slight right at fork onto I 5 Truck
0.3 mi·17 sec·I 5 Truck
Exit 158Toward I 405 SouthUse the straight / slight right lanes.
10
Keep slight left at fork onto I 5 Truck
25 mi·29 min·I 5 Truck
Use the straight / slight right lanes.
11
Keep slight left at fork onto I 5
1.3 mi·1 min·Golden State Freeway
Toward CA 60 East, I 5 South: Pomona, Soto Street, Santa AnaUse the slight left / straight lanes.
12
Merge onto I 5
26 mi·30 min·Santa Ana Freeway
Use the straight / slight right lanes.
13
Keep slight right at fork onto I 5
0.2 mi·16 sec·Santa Ana Freeway
Use the straight / slight right lanes.
14
Take the exit
0.8 mi·57 sec
Toward Broadway, Main Street, Santa AnaUse the straight / slight right lanes.
15
Keep slight left at fork
0.1 mi·10 sec
Use the straight / slight right lanes.
16
Keep slight left at fork
0.2 mi·12 sec
Toward I 5 South
17
Merge onto I 5
0.8 mi·54 sec·Santa Ana Freeway
18
Keep slight right at fork onto I 5
0.8 mi·52 sec·Santa Ana Freeway
19
Keep slight right at fork onto I 5
1.2 mi·1 min·Santa Ana Freeway
Use the straight / slight right lanes.
20
Take the exit
0.7 mi·1 min
Exit 102Toward Newport AvenueUse the slight right lane.
21
Turn right onto Newport Avenue
0.4 mi·44 sec·Newport Avenue
Use the right lane.
22
Turn left onto Walnut Avenue
2.2 mi·4 min·Walnut Avenue
23
Turn left onto Jamboree Road
0.5 mi·37 sec·Jamboree Road
Toward CA 261 Toll North: Jamboree Road, RiversideUse the left lane.
24
Take the exit
0.3 mi·21 sec
Toward I 5 South
25
Merge onto I 5
5.5 mi·6 min·Santa Ana Freeway
Use the straight / slight right lanes.
26
Keep slight left at fork onto I 5
0.8 mi·55 sec·Santa Ana Freeway
Use the straight / slight right lanes.
27
Merge onto I 5
76 mi·1 hr 29 min·San Diego Freeway
Use the straight / slight right lanes.
28
Take the exit
0.2 mi·28 sec
Exit 17Toward Front Street, Civic Center, 2nd AvenueUse the straight / slight right lanes.
29
Keep slight right at fork
0.1 mi·14 sec
Toward Front Street, Civic Center
30
Continue on Front Street
0.5 mi·1 min·Front Street
Use the straight / left lanes.
31
Arrive at destination
Front Street
Trip Plan
Given the 8-hour 57-minute duration, splitting this 478.7-mile drive over two days is highly recommended. Aim to depart early in the morning to maximize daylight driving and avoid heavier traffic, especially as you approach urban areas. Plan for your two stops strategically, perhaps breaking the journey roughly in half to coincide with meal times or to stretch your legs. Keep an eye on your fuel gauge, as the longest stretch without a significant change in road is 271.8 miles on the Westside Freeway; ensure you refuel before reaching that point to stay within your estimated $110 fuel budget.
Morning Departure
Start early — leave by 6-7 AM to arrive at a reasonable hour.
Evening Departure
This is a long drive — plan for a morning departure or consider splitting it into two days.
This drive is better paced as a 2-day trip.
Plan roughly 2 meaningful breaks for fuel, food, and rest.
The halfway point lands around 239.3 miles from Thornton, CA, or about 4h 18m into the drive.
The longest continuous stretch on this route runs about 271.8 miles.
Consider an overnight stop or starting very early.
Departure
Before you leave
Start with fuel, water, and navigation already sorted so the first hour feels easy.
First stop
Around 105 miles or 1h 54m in
Use this first pause for coffee, a restroom break, and a quick traffic check ahead.
Halfway reset
Around 239.3 miles or 4h 18m in
This is the best place for your longest stop, a real meal, and a full fuel check.
Overnight split
Day 1 wrap after about 239.3 miles or 4h 18m
Stop before fatigue turns the last few hours into a grind. You want day two to start fresh, not just resumed.
Final approach
Final hour starts around 7h 46m
Traffic, exits, and arrival timing usually matter more near San Diego, CA than in the middle of the route.
Before You Leave
+
Open the route before leaving Thornton, CA so your first major turns are already loaded.
+
Leave with enough water and a charging cable within reach, not packed away.
+
Check your fuel range against the first long segment, especially if you are starting outside city service areas.
+
Pick one backup stop option before the midpoint in case traffic changes your pacing.
+
Treat this as a 2-day road trip and book the overnight stop before the busiest arrival window.
Day 1
Settle into the route from Thornton, CA
Aim for roughly 239 miles and 4.5 hours of wheel time on this day.
Day 2
Finish the approach into San Diego, CA
Aim for roughly 239 miles and 4.5 hours of wheel time on this day.
Your first comfortable stop window is around 105 miles from Thornton, CA.
This route usually feels better as a 2-day drive than as one long push.
Plan about 2 real breaks rather than only quick fuel stops.
The longest stretch is on Westside Freeway for about 271.8 miles.
Where to Stop
Rest stops, refuel points, and overnight suggestions along this route.
Place data sourced from public business listings. Hours and availability may vary.
Heads-up: tricky spots
5 of 27
5 decision points cluster between mile 334.9 and 477.8 — GPS handles the exact turns, but know they're coming. Your lane choice matters more than the turn itself.
8
334.9 mi into trip|~6h 5m in|I 5 Truck
Keep slight right at fork onto I 5 Truck toward I 405 South
Highway fork - watch signs carefully. Lane positioning matters here
Use the straight / slight right lanes.
Exit 158
Toward I 405 South
8
359.9 mi into trip|~6h 34m in|I 5 / Golden State Freeway
Keep slight left at fork onto I 5 / Golden State Freeway toward CA 60 East, I 5 South: Pomona, Soto Street, Santa Ana
Highway fork - watch signs carefully. Lane positioning matters here. Multiple destination signs - pick the right one
Use the slight left / straight lanes.
Toward CA 60 East, I 5 South: Pomona, Soto Stre...
7
387.1 mi into trip|~7h 6m in
Take the exit toward Broadway, Main Street, Santa Ana
Exit ramp - move to the correct lane early. Lane positioning matters here. Multiple destination signs - pick the right one
Use the straight / slight right lanes.
Toward Broadway, Main Street, Santa Ana
8
394.3 mi into trip|~7h 17m in|Jamboree Road
Turn left onto Jamboree Road toward CA 261 Toll North: Jamboree Road, Riverside
Lane positioning matters here. Multiple destination signs - pick the right one
Use the left lane.
Toward CA 261 Toll North: Jamboree Road, Rivers...
8
477.8 mi into trip|~8h 55m in
Take the exit toward Front Street, Civic Center, 2nd Avenue
Exit ramp - move to the correct lane early. Lane positioning matters here. Multiple destination signs - pick the right one
Use the straight / slight right lanes.
Exit 17
Toward Front Street, Civic Center, 2nd Avenue
Fuel & Cost
Regular Gas
$110.03 one way
$220.05 round trip
$5.84/gal25.4 MPG avg168 kg CO2
Fuel Type
$/gal
One Way
Round Trip
midgrade
$6.02
$113.38
$226.76
premium
$6.18
$116.41
$232.83
diesel
$5.61
$105.69
$211.38
No toll roads detected on this route.
Estimated Trip Cost (one way, 1 person)
Fuel
$110
Hotel (1n)
$80–$140
Meals
$50–$100
Total
$240–$350
Rough estimate based on US averages. Hotel $80–$140/night, meals $25–$50/day.
Estimated CO2 emission: 167.5 kg one way.
Prices: EIA weekly data, 2026-04-13.
Driving Electric?
About $50 in charging
· 1 stop
· 66% less CO2
Vehicle Type
kWh
Stops
DC Fast
Home Charge
Average EV
143.6
1
$50.26
$22.98
Efficient EV
119.7
1
$41.89
$19.15
EV Truck/SUV
191.5
2
$67.02
$30.64
Gas CO2
167 kg
EV CO2
56 kg (66% less)
Plan for 1 charging stop. A 30-minute DC fast charge mid-route should be enough to complete the trip comfortably.
DC fast charging avg $0.35/kWh. Home charging avg $0.16/kWh. US grid CO2: 0.39 kg/kWh.
Travel Intel
Current conditions at both ends of the drive.
Forecast as of Apr 17, 2026
Origin
Thornton, CA
Late night
in Thornton on Tuesday
Local time
2:36 AM
PDT
Current temp
75°F
Unavailable
Live forecast
Destination
San Diego, CA
Late night
in San Diego on Tuesday
Local time
2:36 AM
PDT
Current temp
55°F
Partly Cloudy
SE 5 mph0% chanceLive forecast
Wind Advisory
Wind Advisory issued April 17 at 3:02AM MST until April 17 at 1:00PM MST by NWS Phoenix AZ
Wind Advisory
Wind Advisory issued April 17 at 2:56AM PDT until April 17 at 2:00PM PDT by NWS Los Angeles/Oxnard CA
Seasonal Notes
Summer travel usually means heavier construction, hotter rest stops, and busier weekend traffic around major cities.
Winter travel shortens daylight, so a route that looks manageable on paper can feel much longer after dark.
Holiday weekends tend to make both departure and arrival windows slower than the raw route time suggests.
For long drives, weather on day two can matter just as much as conditions at departure, so check the whole travel window rather than only the first day.
Time zone
Same local time
Origin and destination are on the same clock, so arrival timing is easier to judge at a glance.
Temperature spread
20 degrees cooler at arrival
A meaningful temperature swing is a good cue to rethink layers, water, and how soon you want to arrive.
Road read
8h 57m on the road
This is long enough that the arrival forecast matters almost as much as departure conditions. Recheck both ends before you roll.
Weather data from the National Weather Service. Conditions may change; check closer to your travel date.
National Parks Near This Route
Worth a detour if your schedule allows.
Cabrillo National Monument
National Monument
In 1542, Juan Rodriguez Cabrillo climbed out of his boat and onto shore, becoming the first European to set foot on what is now the West Coast of the United States. Cabrillo National Monument not only...
5 mi from route
~13 min detour
$20
near mile 478.7
Park Closure: Park Auditorium Closed Until Further Notice
The Santa Monica Mountains offer easy access to surprisingly wild places. Experience the famous beaches of Malibu or explore more than 500 miles of trails. The park abounds with historical and cultura...
22 mi from route
~55 min detour
Free
near mile 330.1
Yes, we can! Widely recognized as the most important Latino leader in the United States during the twentieth century, Cesar Chavez led farm workers and supporters in the establishment of the country's...
29 mi from route
~72 min detour
Free
near mile 264.1
Park data from the National Park Service API. Alerts update every 2 hours.
More Details
What kind of drive is this?
Expect a predominantly highway-focused drive on this route, with 99% of the journey utilizing major freeways. You'll spend most of your time on the Westside Freeway, I 5 Truck, and the San Diego Freeway. The character of the drive is largely consistent, characterized by high speeds and efficient travel. The longest uninterrupted stretch is a significant 271.8 miles on the Westside Freeway, meaning you'll need to plan your breaks accordingly. While not designed for leisurely sightseeing, this route prioritizes getting you from point A to point B smoothly and directly.
99% highway — fuel and pacing are the main things to plan.
31 navigation steps total — most of the decisions cluster near the start and finish.
Longest single stretch: 271.8 mi on Westside Freeway.
How Hard Is This Drive?
10/10
This is a straightforward highway drive that stays mostly on Westside Freeway and I 5 Truck. This route has several spots where lane changes, forks, or exits need your full attention. The trickiest moment comes around 334.9 miles in near I 5 Truck.
Driving Effort10/10
High effort - long or complex enough to need steady focus all day
Balances navigation complexity with total wheel time.
This is a demanding drive. With 27 significant decision points across 478.7 miles, you will need to stay alert - especially through interchange areas and urban stretches. Consider splitting it into segments if you are not comfortable with fast highway navigation.
Where does it get tricky?
The main spots that need attention: at 334.9 miles (I 5 Truck): Highway fork - watch signs carefully. Lane positioning matters here; at 359.9 miles (I 5 / Golden State Freeway): Highway fork - watch signs carefully. Lane positioning matters here. Multiple destination signs - pick the right one; at 387.1 miles: Exit ramp - move to the correct lane early. Lane positioning matters here. Multiple destination signs - pick the right one.
Towns Mentioned on Route Signs
Based on OSRM destination-sign hints, not a full list of every settlement the road passes.
Between Thornton, CA and San Diego, CA, road signs point toward Santa Ana, Broadway and Riverside.
From balmy beaches with a laid-back attitude to a gleaming modern image, San Diego offers much for the tourist to enjoy. Situated on the Southern California seacoast, San Diego is the second largest city in the state, with 1.4 million residents (2020), and has long attracted travelers for its ideal climate, miles of beaches, and location on the Mexican border right across from Tijuana.
But there's much more here than surfer culture and a quick hop across the border. A rich maritime and military heritage lives on in San Diego, which is home to the Pacific Fleet of the United States Navy. The city has also become known for its part in the wildlife conservation movement, owing to the presence of the world-renowned San Diego Zoo and Safari Park and the Scripps Institution of Oceanography. Natural scenery abounds from rocky tidepools and seaside cliffs to desert hills and canyons inland.
Top landmarks
•Balboa Park — historic park in San Diego, California
•Cabrillo National Monument — National Monument of the United States and historic district
The longest stretch is about 271.8 miles on Westside Freeway. The full list of main roads is in the Roads section above.
Yes — a 2-day pace is more comfortable than one long haul. A sensible stopping point is after roughly 239 miles on day one.
Yes — we found about 43 rest areas or service plazas within a short detour of the route (from OpenStreetMap). See the Rest Stops tab under Nearby Places for locations and mile markers. Plan to stretch, use the bathroom, and top off fluids every 2–3 hours on longer drives.
It helps. This route has a higher-than-average number of complex decision points, which get harder in the dark. If the last hour of the trip is on surface roads or mountain grades, aim to arrive at San Diego, CA before sunset when you can. Check the Trip Plan for departure windows that land you in daylight.
Only with planning. This is a long drive for kids — consider splitting it into two days rather than pushing through. Plan at least 2 meaningful breaks. There are 43 rest areas along the route for bathroom stops.
The main spots that need attention: at 334.9 miles (I 5 Truck): Highway fork - watch signs carefully. Lane positioning matters here; at 359.9 miles (I 5 / Golden State Freeway): Highway fork - watch signs carefully. Lane positioning matters here. Multiple destination signs - pick the right one; at 387.1 miles: Exit ramp - move to the correct lane early. Lane positioning matters here. Multiple destination signs - pick the right one.
Yes — Cabrillo National Monument, Santa Monica Mountains National Recreation Area and César E. Chávez National Monument. See the National Parks section for detour distances and tips on detours.
Not recommended in a single day. At 9.0 hours each way, a round trip means 17.9 hours of driving — that is an unsafe level of fatigue for most drivers. Plan at least one night at San Diego, CA before the return drive.
