Unnamed Thermal Spring

Lake County County, California · Near Lucerne
39.2000°N, 122.7250°W · 2,244 ft
90°F 2,244 ft Open Roadside US Forest Service Camping nearby (7.1 mi)

This 90-degree thermal spring flows 80 meters from Twin Valley Road in Mendocino National Forest, gaining 30 degrees above ambient temperature in Lake County's cool mountain climate. The roadside location offers easy access to forested high country managed for multiple uses.

The spring emerges at 2,244 feet elevation within dense Mendocino forest, surrounded by mixed conifer stands and mountain meadows. Clear water rises from the thermal source, steaming in the cool mountain air that averages just 59.6 degrees annually. The Twin Valley Road corridor provides straightforward vehicle access without significant approach effort.

History of This Spring

Mendocino National Forest's thermal springs reflect the region's complex geology of volcanic and geothermal activity. This spring flows on federally managed land designated for balanced recreation and resource extraction, where watershed management takes priority over single-use preservation.

The spring sits on U.S. Forest Service land open to public access year-round. Winter snow accumulation reaches 20 inches, making December through February challenging for visits. Bring water shoes for exploring the thermal pools among the surrounding rocks.

Is this spring worth visiting?

Best for

  • Warm-water soaking
  • Easy day trips
  • Overnight camping trips
This spring is well suited for warm-water soaking and easy day trips.
Monthly Climate
46°
Jan
46°
Feb
48°
Mar
55°
Apr
61°
May
72°
Jun
78°
Jul
78°
Aug
72°
Sep
62°
Oct
51°
Nov
45°
Dec
Annual Precip: 31.5 in Annual Snow: 20.0 in
Best Time to Visit
December Air 45°F · Water 90°F · +45° contrast
January Air 46°F · Water 90°F · +44° contrast
February Air 46°F · Water 90°F · +44° contrast
December offers 33°F more contrast than August
Nearby Camping
Letts Lake Campground 7.1 mi away

Overview This location is available on a first-come, first-served basis only. Visitors are required to physically arrive at the campground to purchase and claim a site.Once on-site, you are able to pay for your campsite(s) by scanning a QR code using the Recreation.gov mobile app, and the Scan and Pay feature.In order to utilize Scan & Pay on site, you will need to first download the free Recreation.gov mobile app https://www.recreation.gov/mobile-app prior to your arrival as some remote area...

Reservable Yes
Reserve on Recreation.gov →
What to Bring
Swimsuit & towel
Water bottle Stay hydrated, especially in hot water
Camping gear Nearby camping at Letts Lake Campground
Trash bag Pack out what you pack in
References
USGS Quad: (CLEARLAKE OAKS 15) · NOAA: 4.0 · AMS Map: UKIAH
Frequently Asked Questions
What is the water temperature at ?
has a water temperature of 90°F (32°C). This is a warm thermal spring.
Where is located?
is located in Lake County, California at 2,244 feet elevation, near Lucerne. Coordinates: 39.2000°N, 122.7250°W.
How do I get to ?
has Roadside road access, with the nearest road being Twin Valley Road (262 ft from the road).
Is free to visit?
has Open access. It is managed by US Forest Service.
Can I camp near ?
Yes, Letts Lake Campground is located nearby (7.1 miles away).
Is it safe to soak at ?
is generally safe for soaking at its recorded temperature. Always tell someone your plans before visiting remote hot springs.
Is crowded?
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 ?
Essentials for : swimsuit, towel, water bottle, camping gear, a trash bag to pack out what you pack in.
Temperature
90°F
Warm Hot Boiling
Water Temp 90°F (32°C)
Avg Air Temp 60°F
Above Ambient +30°F
Good soaking conditions March
Access
Open
Road Access Roadside
Nearest Road Twin Valley Road
Distance to Road 262 ft
Land
Ownership Federal
Agency US Forest Service
Designation National Forest
Unit Mendocino National Forest
Manager US Forest Service
Protection 3 - Protected, subject to extractive use