Unnamed Thermal Spring
This 73-degree spring in Sonoma County wine country, with recent USGS measurements of 32°C, flows at just 340 feet elevation with water 13 degrees warmer than ambient air.
A 145-meter walk from Keiser Lane leads through oak woodlands and vineyard-dotted slopes toward this modest warm spring. The terrain rolls gently beneath mature oaks and scattered madrone trees. The water emerges clear and steady, creating a small warm pool in shade. Nearby vineyards cover the hillsides, evidence of the region's world-class viticulture.
This spring lies within the diverse geology of Sonoma County, where coastal mountain ranges meet inland valleys. The warm water reflects heat from subsurface geology shaped by millions of years of tectonic activity. The region has supported human settlement and agriculture for centuries, from Native Americans through Spanish colonial periods to modern wine production.
The 145-meter walk over moderate terrain is accessible to most visitors. Spring through autumn offers the most pleasant visiting conditions, with mild weather and lower water flow. Winter brings increased rainfall and muddy approaches. Sunset hours create golden light across nearby vineyards.
Is this spring worth visiting?
Best for
- Overnight camping trips
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