Unnamed Thermal Spring

Sonoma County, California · Near Eldridge
38.3570°N, 122.5090°W · 261 ft
70°F 52°F air · Good soaking weather 261 ft Roadside Camping nearby (20.4 mi)

Another unnamed Sonoma County spring, this one right beside a road a mile and a half from Eldridge. The reading on record is 70 degrees, roughly air temperature on a spring afternoon, so think of it as a warm seep. A photo is attached, which is more than most unnamed points get. Ownership and access go unrecorded.

Location

Roadside in the literal sense. The record puts the spring nine feet off the pavement, though it does not name the road. Low valley floor, a few hundred feet up, where winters bring a couple of feet of rain and summers bring none. Snow does not happen here. What surrounds the outlet goes undescribed anywhere on file, so the photo is your best guide to what you will see.

The listed best months run December through February. You can park and look without a walk. No owner is recorded, so keep to the road shoulder unless you learn otherwise. Camping is thin; the only site on file is Oak Shores, twenty miles away and day use by name. No fee is recorded. The water is too cool to count as a soak.

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.

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.

Setting
Valley floor
Gentle slopes rise on both sides.
Highest ground nearby
204 ft above the spring
Within a quarter mile, to the north
Cross-section through the spring

A slice through the ground from south to north, about 0.6 miles end to end.

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

Heat Below
181 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
49°
Jan
51°
Feb
54°
Mar
58°
Apr
63°
May
69°
Jun
71°
Jul
71°
Aug
70°
Sep
65°
Oct
55°
Nov
49°
Dec
Annual Precip: 25.3 in Annual Snow: 0.1 in
Best Time to Visit
January Air 49°F · Water 70°F · +21° contrast
December Air 49°F · Water 70°F · +21° contrast
February Air 51°F · Water 70°F · +19° contrast
January offers 22°F more contrast than August
Current Conditions
52°F
Clear N 0.0 mph 94% Good soaking weather
Tuesday 88° Low 52° Patchy Fog then Sunny
Wednesday 81° Low 50° Patchy Fog then Mostly Sunny 1% precip
Thursday 85° Low 51° Areas Of Fog then Mostly Sunny
Friday 89° Low 51° Areas Of Fog then Mostly Sunny
Saturday 87° Low 52° Areas Of Fog then Sunny
Where to Stay

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Nearby Camping
Oak Shores Day Use Area (Ca) 20.4 mi away

Overview Nestled between Blue Ridge and Cedar Roughs east of Napa Valley, Lake Berryessa provides ample public recreation opportunities. Popular activities on and around the large, yet uncrowded lake include fishing, boating, water skiing, wake boarding, jet skiing, sailing, swimming, kayaking, canoeing, wildlife viewing, hiking, biking and picnicking. The Dufer Point Visitor Center offers year-round interpretive events and exhibits highlighting natural and cultural resources. Lake Berrye...

Reservable Yes
Reserve on Recreation.gov →
Temperature
70°F
Warm Hot Boiling
Water Temp 70°F (21°C)
Avg Air Temp 60°F
Above Ambient +10°F
Mild soaking conditions September
Access
Road Access Roadside
Distance to Road 9 ft
Frequently Asked 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 Sonoma County, California at 261 feet elevation, near Eldridge. Coordinates: 38.3570°N, 122.5090°W.
How do I get to ?
has Roadside road access (9 ft from the road).
Can I camp near ?
Yes, Oak Shores Day Use Area (Ca) is located nearby (20.4 miles away).