Unnamed Thermal Spring

Lake County, California · Near Lucerne
39.2000°N, 122.7250°W · 2,244 ft
90°F 61°F air · Good soaking weather 2,244 ft Open Roadside US Forest Service Camping nearby (7.1 mi)
Aerial view of the ground around the spring LiDAR bare-earth view of the same ground around the spring
Aerial LiDAR bare earth

Drag the handle to compare the two views. The orange dot marks the spring, in a frame about three quarters of a mile wide.

Mendocino National Forest holds this one, about nine miles from Lucerne in Lake County, a spring without a name and with water at ninety degrees. Warm enough for a soak on a cool day. The Forest Service has the land and the record marks it open. Twin Valley Road passes right by.

Location
12 miles from Clearlake Oaks, CA

Twin Valley Road runs a few hundred feet away, so the record files this as roadside. The land designation is National Forest. Elevation is around twenty-two hundred feet. The forest here gets thirty-two inches of precipitation annually and about twenty inches of snow across a winter, enough to matter on a forest road.

Between December and February is the window on record. Letts Lake Campground is around seven miles away. No fee is recorded. The spring sits on open public land, and still there is no chemistry sample on file and no second name. Mind the forecast before driving forest roads in winter.

Terrain

Aircraft with laser scanners measured this ground to within inches. The scan strips out trees and buildings, leaving the bare shape of the land around this spring.

Setting
Canyon floor
Steep ground climbs away on both sides of the spring.
Highest ground nearby
220 ft above the spring
Within a quarter mile, to the north
Cross-section through the spring

A slice through the ground from northwest to southeast, about 0.6 miles end to end.

Elevation data: USGS 3D Elevation Program. Aerial imagery: USGS The National Map. Public domain.

Heat Below
179 milliwatts per square meter of heat flow

That's about 3 times the US average of 65. It's higher than at 98% of the springs on this site.

Heat flow measures the warmth working its way up through the ground from deep inside the earth. Where it runs high, rain and snowmelt that seep down through cracks in the rock come back up hot.

Heat flow estimate: Stanford Thermal Earth Model (Aljubran & Horne, 2024), CC BY 4.0.

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
Current Conditions
61°F
SW 18.0 mph 29% Good soaking weather
Today 87° Low 57° Sunny
Spring is +3° warmer
Wednesday 79° Low 55° Sunny 14% precip
Spring is +11° warmer
Thursday 80° Low 58° Sunny
Spring is +10° warmer
Friday 88° Low 63° Sunny
Spring is +2° warmer
Saturday 89° Low 63° Sunny
Spring is +1° warmer
Nearby Camping
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 →
Temperature
90°F
Warm Hot Boiling
Water Temp 90°F (32°C)
Avg Air Temp 60°F
Above Ambient +30°F
Warm air, warm water September
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
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).