Guyer Hot Springs
Guyer Hot Springs erupts at 158°F near Ketchum in the Sun Valley corridor, one of the hottest thermal sources in the state. The spring sits at 5,920 feet elevation directly off Warm Springs Road, just 22 feet from pavement, where it has been commercially developed for more than a century.
Warm Springs Road follows the creek west from Ketchum, and the spring emerges right at roadside where steam is visible in any weather below 50°F. The water carries 88 mg/L sodium and 76 mg/L sulfate with a pH of 9.1, creating a mildly alkaline soak. At 41°F average annual air temperature and over 115 inches of snow, winter transforms the setting into a snow-walled corridor of steam and warm mist between the road and the creek.
The spring has been a gathering point since at least the late 1800s, when miners and settlers used the naturally heated water. Geologically, it draws from the deep fracture systems along the Big Wood River valley, where the Earth's crust has been thinned and faulted. The 117-degree differential between water and air temperature is among the highest in Idaho, reflecting a deep and powerful geothermal source.
The spring is commercially operated and requires an entry fee. It sits directly off Warm Springs Road, about a mile west of downtown Ketchum. Check current hours and policies before visiting, as access rules change seasonally. North Fork Campground on the Big Wood River is about 12 miles north and offers reservable sites at 6,300 feet.
Is Guyer Hot Springs worth visiting?
Best for
- Observing powerful hot springs
- Easy day trips
- Overnight camping trips
Not ideal for
- Casual soaking
The water at Guyer Hot Springs is alkaline (pH 9.1).
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Overview North Fork Campground is situated on the banks of the beautiful Big Wood River at an elevation of 6,300 feet. Visitors enjoy fishing and tubing on the river and exploring the Harriman Trail.Recreation This site is part of the Sawtooth National Recreation Area, where outdoor activities abound. Fly-fishing for rainbow, brown and brook trout is popular on the Big Wood River, as is float tubing. The 20-mile Harriman Trail leads past the campground, offering excellent hiking and biking...