Mollys Hot Spring
Mollys Hot Spring surfaces at 138 degrees Fahrenheit along South Fork Road in the Warm Lake area of Valley County, where Boise National Forest receives nearly 199 inches of snow per year. That combination of scalding water and massive snowfall creates one of Idaho's most visually dramatic thermal scenes, especially during winter when steam clouds billow against deep snowpack.
At 5,180 feet elevation, the spring sits just 280 feet from the road in a landscape of tall conifers and mountain meadows. Warm Lake itself lies nearby, and the surrounding forest stays wet, receiving 38.5 inches of annual precipitation. The alkaline water, with a pH of 9.3, carries very little calcium at just 1.6 milligrams per liter, leaving the rocks around the source unusually clean compared to more mineral-encrusted springs. In summer, wildflowers fill the roadside clearings; in winter, snow buries everything but the steaming outflow.
The spring's chemistry points to deep circulation through the Idaho Batholith's granitic core. Sodium dominates at 76 milligrams per liter with minimal calcium, a signature of water that has traveled through feldspar-rich rock at high temperatures before surfacing. USGS measurements confirm 59 degrees Celsius. The Warm Lake basin has attracted visitors since the early days of Idaho settlement, and the area's concentration of hot springs reflects a particularly active zone of geothermal upwelling along the South Fork of the Salmon River drainage.
Picnic Point Campground at Warm Lake, under 2 miles away, offers reservable sites at 5,300 feet with boating, fishing, and swimming access. The spring is roadside along South Fork Road, but the 138-degree source temperature is dangerous and requires extreme caution. Roads in this area may close from late fall through spring due to heavy snowfall. Contact the Boise National Forest Cascade Ranger District for current road conditions. Billy Rice Swim Beach near the campground provides a safer warm-water option.
Is Mollys Hot Spring worth visiting?
Best for
- Hot spring soaking
- Easy day trips
- Overnight camping trips
The water at Mollys Hot Spring is alkaline (pH 9.3).
Overview Picnic Point Campground is located on a bluff overlooking beautiful Warm Lake, at an elevation of 5,300 feet. Visitors enjoy boating, fishing, swimming, hiking and viewing local wildlife. Recreation Warm Lake offers great fishing opportunities for cutthroat, rainbow, lake and bull trout. Boating, canoeing and swimming are popular activities. A boat ramp is located at neighboring Shoreline Campground. Billy Rice Swim Beach is within walking distance, offering a day-use site for picni...