# Unnamed thermal spring, California

Unnamed thermal spring in California. 70°F (21°C). Roadside · Public Land. Contra Costa County.

- Page: https://www.soakingsprings.com/hot-springs/california/unnamed-spring-contra-costa-county
- Source: Soaking Springs, researched and maintained by Armen Suny
- Updated: 2026-09-14

## Can you soak at this spring?

The water leaves the ground at 70°F, about as warm as a heated pool. You can drive right up to it. We haven't confirmed whether it has a pool or charges a fee.

## Key facts

| Fact | Value |
|---|---|
| Source water temperature | 70°F (21°C) (USGS record; developed pools are often cooled) |
| Elevation | 665 ft |
| Access | Roadside · Public Land, 57 ft from the nearest road |
| Land | Mount Diablo State Park, SPR |
| County | Contra Costa County |
| Nearest town | Clayton |
| Coordinates | 37.89500, -121.87400 |
| Best months to soak | January, December, February (largest gap between water and average air temperature) |

## About Unnamed thermal spring

Inside Mount Diablo State Park in Contra Costa County, roughly four miles from Clayton, there is an unnamed thermal point with water of about seventy degrees. Tepid. Nothing anyone would sit in, more a warm seep. The state park ground is listed as open, and the point sits a few dozen feet from a road, so reaching it takes little effort. A temperature is on record and little else.

Low hills inside the state park at about 650 feet, no snow, dry apart from winter rain. Fifty-odd feet from the road edge. The California state park system manages the ground. No campground is recorded near this point in our data, and no fee is noted.

The listed window is midwinter, though the roads here stay clear year round. Roadside. State park rules apply. No fee recorded. No camping in the record for this point. The water is not warm enough for a meaningful soak, so come for the curiosity of it.

## Nearby

- Nearest city page: [Hot springs near Antioch](https://www.soakingsprings.com/hot-springs/near/california/antioch), 7 mi away
- State page: [Hot springs in California](https://www.soakingsprings.com/hot-springs/california)
- [Springs, CA](https://www.soakingsprings.com/hot-springs/california/springs-contra-costa-county): Warm, Roadside, near Clayton, Contra Costa County
- [Sulphur Spring, CA](https://www.soakingsprings.com/hot-springs/california/sulphur-spring-2): 75°F source, Roadside, near Waldon, Contra Costa County
- [Byron Hot Springs, CA](https://www.soakingsprings.com/hot-springs/california/byron-hot-springs): 96°F source, Short Walk, near Byron, Contra Costa County
- [Crohare Spring, CA](https://www.soakingsprings.com/hot-springs/california/crohare-spring): 70°F source, Short Walk, near Livermore, Alameda County
- [Unnamed thermal spring, CA](https://www.soakingsprings.com/hot-springs/california/unnamed-spring-solano-county): 73°F source, Roadside, near Benicia, Solano County
- [Vallejo White Sulphur Springs, CA](https://www.soakingsprings.com/hot-springs/california/vallejo-white-sulphur-springs): 68°F source, Roadside, near Vallejo, Solano County

## Questions

**What is the water temperature at ?**
 has a water temperature of 70°F (21°C). This is a warm thermal spring.

**Where is  located?**
 is located in Contra Costa County, California at 665 feet elevation, near Clayton. Coordinates: 37.8950°N, 121.8740°W.

**How do I get to ?**
 has Roadside road access (57 ft from the road).

**Is  free to visit?**
 has Open access. It is managed by SPR.

## Sources

- USGS thermal springs records, Water Quality Portal lab analyses, OpenStreetMap, Wikipedia/Wikidata, NOAA climate normals