Thunderhill Raceway Park

Thunderhill Raceway Park at a glance

Location

Willows, California

Type

road course

Length

2.866 mi (4.612 km)

Turns

16

Direction

clockwise

Surface

asphalt

Opened

1993

Owner

San Francisco Region, Sports Car Club of America

Address

5250 Highway 162

Website

thunderhill.com

Track map and layout

Thunderhill sits in California's Sacramento Valley west of Willows and is really three tracks in one: the original East Circuit (marketed as roughly 3 miles, technically 2.866 miles with 16 turns), the newer 2-mile West Circuit added in 2014, and the combined 5-mile Thunderschleife that links them into the longest permanent road course in the United States. The East course mixes long, sweeping sections with a standout downhill, off-camber corner nicknamed the Cyclone, often compared to Laguna Seca's Corkscrew. The West course is tighter and more technical, built to test precision over outright speed. Because Thunderhill sits well away from residential neighbors, it runs a genuinely 24-hour noise policy, which is why it can host the famous 25 Hours of Thunderhill enduro without the curfews that limit most American circuits.

Named corners and sections

• The Cyclone. A downhill, off-camber corner on the East Circuit often compared to Laguna Seca's Corkscrew.

Configurations

Events and race weekends

Thunderhill's marquee event was the 25 Hours of Thunderhill, run annually from 1998 into the 2020s and billed as the longest automobile race in the United States, taking advantage of the track's round-the-clock noise allowance. The circuit also hosted rounds of the Trans-Am West Coast Series and remains a fixture for Northern California club racing and endurance events year-round.

Getting there and parking

Thunderhill is remote by design, sitting about 7 miles west of Willows in rural Glenn County, roughly 90 minutes north of Sacramento. Most visitors drive in via I-5; the nearest commercial airport is Sacramento International.

• Sacramento International Airport (SMF)

The track's rural location and 24-hour noise allowance make it one of the few U.S. circuits that can run true overnight endurance racing -- plan for limited nearby services and stock up in Willows before heading out.

Hotels and camping near Thunderhill Raceway Park

Because Thunderhill is far from any large town, on-site camping is heavily used by racers and track-day drivers during event weekends, especially for the overnight 25 Hours enduro. Visitors who want a hotel typically stay in Willows or Chico.

Where to look

Willows, California is the closest town; Chico offers a wider range of hotels roughly 30-40 minutes away.

Track days, driving experiences and lap records

Thunderhill is one of Northern California's busiest HPDE and club-racing venues, hosting frequent events from NASA and SCCA as well as dedicated track-day operators such as Hooked on Driving. The East, West and combined Thunderschleife configurations give organizers flexibility to run different layouts depending on the event and skill level.

Who runs days here

• Hooked on Drivingcar
• NASA Northern Californiacar
• SCCA San Francisco Regioncar

Spectator guide

Thunderhill is more of a working race track than a stadium venue -- spectator infrastructure is modest compared to major professional circuits, and most fans watch from open viewing areas rather than large grandstands.

Best places to watch

Elevated viewing near the Cyclone on the East Circuit gives a good look at one of the track's most demanding corners.

Weather

• Dec: cold nights and frequent Central Valley fog for the overnight 25 Hours enduro
• Jun-Aug: hot, dry Sacramento Valley summers, often exceeding 95°F

History of Thunderhill Raceway Park

Origins

Thunderhill Raceway Park broke ground in January 1993 and opened that October, built by the San Francisco Region of the Sports Car Club of America on open land in California's Sacramento Valley, west of the small town of Willows. The remote site was chosen partly because it kept the track far enough from residential development to avoid the noise curfews that constrain most American circuits, a decision that would later define much of Thunderhill's identity.

Growth of the complex

The original 3-mile East Circuit built the track's early reputation among Northern California club racers, but Thunderhill expanded significantly in 2014 with the addition of a second, more technical 2-mile West Circuit. The two can be linked into a combined 5-mile configuration nicknamed the Thunderschleife, which is recognized as the longest permanent road course in the United States. Because the property carries a genuinely round-the-clock noise allowance, Thunderhill became the home of the 25 Hours of Thunderhill, an endurance race launched in 1998 that ran through the night without the curfew breaks required at almost every other American track and earned a reputation as the longest automobile race held in the country.

Present day

Thunderhill remains owned and operated by the SCCA's San Francisco Region and functions as a working, community-oriented racing facility rather than a spectator-driven stadium track. It hosts a packed calendar of club racing, endurance events, motorcycle training, drifting and karting alongside a very active HPDE and track-day scene run by organizations such as NASA, SCCA and Hooked on Driving. The Cyclone, a downhill off-camber corner on the East Circuit often compared to Laguna Seca's Corkscrew, remains the track's best-known feature among drivers who return year after year for its combination of flexible configurations and genuinely 24-hour access.

Frequently asked questions

Other tracks nearby

• Sonoma Raceway · 96 mi · road course
• WeatherTech Raceway Laguna Seca · 207 mi · road course
• Willow Springs International Raceway · 392 mi · road course
• Portland International Raceway · 419 mi · road course
• Las Vegas Motor Speedway · 458 mi · oval
• Grand Prix of Long Beach · 460 mi · street circuit