At 163°F, the source water at Castle Rock Springs is hot enough to cause burns. Some hot springs this hot have cooler side pools or downstream areas suitable for soaking — always test the water temperature before entering.
Castle Rock Springs produces 163-degree water from Lake County's Mayacamas Mountains just 70 feet roadside from Castle Spring Road. This thermal feature flows approximately 105 degrees above ambient in a landscape transitioning between oak woodlands and mixed conifer forest.
The spring sits at 2,380 feet elevation in the geothermal Lake County zone where volcanic rocks and fault structures create favorable conditions for thermal features. The immediate setting displays mineral-altered ground, steam vents, and the sensory experience of hot-water flow through temperate forestry landscape with regular seasonal precipitation.
History of Castle Rock Springs
Castle Rock Springs reflects the same major geothermal system that feeds Castle Hot Springs. Lake County's thermal features developed along fault zones cutting through the Mayacamas volcanic sequence, creating accessible yet geologically significant ground manifestations of deep-seated heat sources.
Park safely off Castle Spring Road and approach the spring carefully—the water reaches dangerous temperatures. This roadside spring is accessible year-round but most pleasant in shoulder seasons when humidity levels are moderate. Warm Springs Recreation Area (25 kilometers away) provides day-use amenities near Lake Sonoma.|
Is Castle Rock Springs worth visiting?
Best for
Observing powerful hot springs
Easy day trips
Overnight camping trips
Not ideal for
Casual soaking
Castle Rock Springs is well suited for observing powerful hot springs and easy day trips.
Monthly Climate
45°Jan
46°Feb
47°Mar
53°Apr
59°May
69°Jun
74°Jul
74°Aug
69°Sep
61°Oct
51°Nov
44°Dec
Annual Precip: 30.0 inAnnual Snow: 5.1 in
Best Time to Visit
JanuaryAir 45°F · Water 163°F · +119° contrast
DecemberAir 44°F · Water 163°F · +119° contrast
FebruaryAir 46°F · Water 163°F · +117° contrast
January offers 30°F more contrast than August
Nearby Camping
Warm Springs Rec Area15.6 mi away
Overview
Warm Springs Recreation Area is a day-use park located at Lake Sonoma, which is just a 45 minute drive north of Santa Rosa and a 2 hour trip from San Francisco. There is no overnight camping available at this facility
World famous vineyards and a land rich in history surround the lake, where visitors enjoy boating, fishing and exploring the area's extensive trail network.Recreation
The Woodland Ridge Nature Trail begins at the park and winds up the ridge, rewarding hikers with great...
What is the water temperature at Castle Rock Springs?
Castle Rock Springs has a water temperature of 163°F (73°C). This is considered a hot spring, well above body temperature.
Where is Castle Rock Springs located?
Castle Rock Springs is located in Lake County, California at 2,380 feet elevation, near Cobb. Coordinates: 38.7680°N, 122.7170°W.
How do I get to Castle Rock Springs?
Castle Rock Springs has Roadside road access, with the nearest road being Castle Spring Road (230 ft from the road).
Can I camp near Castle Rock Springs?
Yes, Warm Springs Rec Area is located nearby (15.6 miles away).
Is it safe to soak at Castle Rock Springs?
The water at Castle Rock Springs reaches 163°F, which can cause severe burns. Do not enter the source pool directly — look for cooled side pools or downstream areas where the water has cooled to a safe temperature. Access may be on private land or unconfirmed — verify current conditions before visiting. Always tell someone your plans before visiting remote hot springs.
Is Castle Rock Springs crowded?
Castle Rock Springs is accessible from a paved road, making it easy to reach. Weekends and holidays may be busier — consider visiting on a weekday for a quieter experience.
What should I bring to Castle Rock Springs?
Essentials for Castle Rock Springs: swimsuit, towel, water bottle, camping gear, a trash bag to pack out what you pack in. The water is over 110°F — test the temperature before entering and watch for scalding near the source.