The west coast road trip: Seattle to San Diego by I-5 or US 101

A west coast road trip from Seattle to San Diego crosses three states and is about 1,255 miles on I-5 alone, about 23 hours 50 minutes of driving before any detour. We would give the stop-by-stop version 13 nights, or 14 with Olympic or Mount Rainier, and that count is our judgement. The US 101 version adds one or two more.

We read the figures below on 5 November 2026 on the National Park Service, Washington and Oregon road, tax and fire-marshal pages, Caltrans, the Golden Gate Bridge district and NOAA. Distances are from our own routing unless a Park Service figure is named. Our own drive times are rounded down and assume no traffic and no stops.

Is I-5 or Highway 101 the better road for a west coast road trip?

In our view I-5 suits fixed days and US 101 suits a trip where the coast is the point, and a US 101 road trip is the slower choice. The gap is largest in the north: US 101 adds about 101 miles between Seattle and San Francisco, and about 41 miles between San Francisco and Los Angeles.

The I-5 total is a direct route that skips San Francisco, which is why it is shorter than its three rows added up. The last US 101 row is our sum of the two coast stretches and the Los Angeles to San Diego leg. US 101 to San Francisco and I-5 after it is about 1,409 miles and about 30 h 50 min. Our routing cannot be told to stay on US 101. Each coast figure is therefore the route through towns on it, and the California mileage is a floor.

US 101 has one weak point. Last Chance Grade, between Klamath and Crescent City, is where a closure becomes an eight-hour detour. Caltrans' release of 20 August 2026 says the detour runs through Oregon and inland Northern California. Construction of the tunnel there is "currently anticipated to begin in 2031".

What are the legs of the Seattle to San Diego road trip?

The Seattle to San Diego road trip runs in six legs, and the table adds a winter way to Crater Lake. It goes by I-5 to Portland, then to Crater Lake, Redwood, San Francisco, Los Angeles and San Diego. Seattle to Portland is one road either way, so the choice between I-5 and US 101 starts after Portland.

The six legs add up to about 1,457 miles and about 30 h 30 min in summer, or about 1,494 miles in winter. That is more than the 1,255 miles of I-5 alone, because the detours to Crater Lake and the Redwood coast leave the freeway.

Our routing and the Park Service disagree on Crescent City to Crater Lake by about 36 miles. The road is US 199 and Highway 62, and the Park Service figure is the one to plan on.

Two more stops are a choice, and neither sits on the sum above. Olympic National Park is about 139 miles and about 3 h 10 min from Seattle to Port Angeles. Mount Rainier National Park is 107 miles and about 2½ hours from Seattle to Paradise by the park's own figures. Take one, not both, unless the trip has the nights to spare.

How many nights does the west coast road trip need?

The west coast road trip needs 13 nights on the I-5 line, or 14 with Olympic or Mount Rainier. That count is ours. It rests on the drive times above and one full day at each stop that is not also a driving day.

The US 101 version adds one night on the Oregon coast and a second on the Northern California coast. The stretch to San Francisco is about 5 h 40 min longer. Our guide to the California road trip covers the loop around Yosemite and Sequoia. The Pacific Coast Highway covers Highway 1 between Los Angeles and San Francisco.

Which months suit the full Seattle to San Diego drive?

July to mid-September suits the full drive, by our reading of the road dates. Crater Lake's Rim Drive is open from "mid-June or early July" until about 1 November. Mount Rainier's Sunrise Visitor Center is generally open July through mid-September.

Late June and early to mid-October work with the Rim Drive partly open or the first snow close. From mid-November to May the line needs chains in several places, and the Rim Drive is shut.

Oregon's smoke record overlaps July to mid-September. The state's environment agency counted 143 days of air quality unhealthy for sensitive groups or worse at Medford in 2013 to 2025. The figure for 2000 to 2012 was 22. Portland had 29 against 3. Its 2025 report defined the season as 1 June to 25 October. That year was mild, with one such day at Medford and none at Portland. We read no official smoke figure for Washington or California.

What closes on the west coast road trip in winter?

Crater Lake's Rim Drive and North Entrance Road close for the season, and on 5 November 2026 they were closed. The park's alert says they will not reopen until "mid-June or early July depending on the snowpack". An older Park Service page, last updated in August 2023, says the roads reopen in stages from May. Plan on the alert.

Rim Village stays reachable all winter by Highway 62 from the south and west. Chains or traction tires are required on all vehicles in the park during winter. No fuel is sold inside the park. The nearest is the Prospect service station, 29 miles from the south fee booth.

Mount Rainier requires chains on every vehicle, four-wheel drive included, from 1 November to 1 May. Winter vehicle access is only from the Nisqually Entrance. The gate above Longmire is a day-by-day matter: on 4 November it closed for the night and was projected to open at 9:00 a.m. on 5 November. Read the park's road-status page the evening before.

Olympic has two dated problems. Hurricane Ridge Road was closed for ice on Wednesday 4 November 2026, with no winter schedule given. On US 101 south of Forks, the Hoh River Bridge has been one lane since 14 July 2026. It runs on signals with a 25 mph limit "until a permanent repair is made". The state gives no date for that repair.

California is the gap, because this page makes no claim about current closures on I-5 or US 101 there. Check Caltrans's QuickMap before each California leg.

What does the Siskiyou Summit mean for I-5 in winter?

The Siskiyou Summit on I-5 stands at 4,310 feet, on the Oregon side of the California line. On 5 November 2026 TripCheck's posting for the stretch from the California line to the Talent exit read "Carry chains or traction tires regardless of conditions". The reporting stations showed bare pavement and 39°F.

The Oregon Department of Transportation calls conditional closures on I-5 through the Siskiyou Pass "frequent in the winter". Oregon lets cars of 10,000 pounds or less that are not towing use traction tires in place of chains. Studded tires are legal from 1 November to 31 March.

Caltrans' own rules are stricter in one way. Its R-2 level exempts four-wheel drive with snow-tread tires on all four wheels from fitting chains, but the car must still carry them. Its chain page does not name the Siskiyou County section of I-5, so we have no California posting for it.

What changes at each state line on a west coast road trip?

Three things change: sales tax, fuel pumps and tolls. Oregon has no general sales tax, according to its Department of Revenue. Washington's state sales tax is 6.5% under state law. Hire cars carry an extra 11.9% through 31 December 2026, then 9.9% from 1 January 2027. Rates for California cities are in our guides to San Francisco, Los Angeles and San Diego.

Oregon's self-serve fuel rule works county by county. In 20 rural counties, including Clatsop, Curry and Klamath, anyone can pump their own fuel at any time. In 16 others, including Multnomah, Jackson and Douglas, a station may make only half its pumps self-serve. The price is the same either way, and diesel drivers may self-fuel everywhere.

The whole line keeps Pacific time. Clocks went back on Sunday 1 November 2026 and go forward on 14 March 2027, a date that is our arithmetic from the second-Sunday rule.

Which tolls does a west coast road trip meet?

The Golden Gate Bridge is the one toll that sits on the route, and it is charged southbound only. From 1 July 2026 a car pays $10.25 with FasTrak, $10.50 with a plate account or a one-time payment, and $11.25 by invoice. There is no cash.

Hire companies add fees if the car goes through their own tolling programme. The bridge district says to opt out and pay online within 48 hours after crossing, or up to 30 days before. Our guide to renting a car in the USA covers the counter, and we read no company's one-way drop fee for this trip.

Two Washington tolls matter only on detours. The SR 520 floating bridge from Seattle to Bellevue is tolled in both directions, at $4.90 on weekday peaks with a Good To Go! pass and $6.90 by Pay By Mail. The SR 16 Tacoma Narrows Bridge on the way to Olympic is tolled only toward Tacoma, at $4.50 with a pass. We read no Oregon or California toll on I-5 or US 101.

What do the parks on the west coast road trip cost?

None of Olympic, Mount Rainier, Crater Lake or Redwood is on the list of 11 parks that carry the $100 non-resident surcharge. Our guide to national park fees for international visitors explains the list and the $250 pass.

Mount Rainier requires no timed-entry reservation in 2026. The Park Service has not said whether 2027 differs.

What do NOAA normals say about the weather along the line?

The weather along the line changes by more than 30°F between the coast and the mountains in the same month. January highs run from 66 at San Diego to 33 at Crater Lake. The table gives NOAA's 1991 to 2020 normals in degrees Fahrenheit, high and low.

Crater Lake's July high is the lowest of the six stations. San Francisco is cooler in July than in October. Seattle's July rain is 0.60 inches. NOAA's headquarters normal for Crater Lake snow is 463 inches a year. The Park Service puts the average at 41 feet, so about 40 feet is a fair figure either way.