San Antonio Warm Spring
San Antonio Warm Spring flows at 101°F (38.5°C per USGS) within the Valles Caldera National Preserve at 8,431 feet. The water is 56°F above local ambient, mildly acidic at pH 6.7, and low in dissolved minerals. Managed by the National Park Service, the spring has roadside access just 44 meters from the road.
The spring surfaces inside the Valles Caldera, a massive volcanic depression in the Jemez Mountains of northern New Mexico. At 8,431 feet, the caldera floor supports expansive mountain meadows ringed by mixed-conifer forest. The area receives 23 inches of rain and 53 inches of snow annually, creating a lush landscape sharply different from the surrounding desert lowlands. The East Fork of the Jemez River and several tributaries drain the caldera, and elk herds are a common sight across the grasslands.
The Valles Caldera formed roughly 1.25 million years ago in a catastrophic eruption. San Antonio Warm Spring draws its heat from the residual magmatic system beneath the caldera floor. The preserve was a private ranch (Baca Ranch) for over a century before Congress acquired it in 2000. The National Park Service assumed management in 2015. The spring carries permanent protection status with open public access, subject to preserve regulations and seasonal closures.
Check Valles Caldera National Preserve operating hours and seasonal road closures before visiting; the preserve gate controls entry and winter access is limited. At 8,431 feet, afternoon thunderstorms are common in July and August, and temperatures drop sharply after sunset even in summer. San Antonio Campground, 12 km south in the Santa Fe National Forest, is the nearest reservable camping option and operates May through October.
Is San Antonio Warm Spring worth visiting?
Best for
- Hot spring soaking
- Easy day trips
- Overnight camping trips
The water at San Antonio Warm Spring is slightly acidic (pH 6.7).
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Overview San Antonio Campground is adjacent to the San Antonio River, tucked into a forest of ponderosa pine at 7,600 feet above sea level. This popular campground is open from May through October in the Santa Fe National Forest. Visitors should be prepared for hot summer days and cool nights. San Antonio Campground was completely rebuilt and reopened in August 2010. It is designated as a reduced impact and recycle campground.Recreation A paved walking trail along the river provides access f...