At 158°F, the source water at Guyer Hot Springs is hot enough to cause burns. Some hot springs this hot have cooler side pools or downstream areas suitable for soaking — always test the water temperature before entering.
File:Warm Springs Run.jpg — cc by-sa 4.0
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.
History of Guyer Hot Springs
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
Guyer Hot Springs is well suited for observing powerful hot springs and easy day trips.
Monthly Climate
22°Jan
24°Feb
30°Mar
36°Apr
45°May
56°Jun
67°Jul
66°Aug
56°Sep
42°Oct
29°Nov
19°Dec
Annual Precip: 23.4 inAnnual Snow: 115.3 in
Best Time to Visit
DecemberAir 19°F · Water 158°F · +139° contrast
JanuaryAir 22°F · Water 158°F · +136° contrast
FebruaryAir 24°F · Water 158°F · +134° contrast
December offers 48°F more contrast than July
USGS Field Measurements
Recent Temperature
158.9°F
(70.5°C)Measured May 03, 1988
Water ChemistrySampled 1988-05-03
The water at Guyer Hot Springs is alkaline (pH 9.1).
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...
What is the water temperature at Guyer Hot Springs?
Guyer Hot Springs has a water temperature of 158°F (70°C). This is considered a hot spring, well above body temperature.
Where is Guyer Hot Springs located?
Guyer Hot Springs is located in Blaine County, Idaho at 5,920 feet elevation, near Ketchum. Coordinates: 43.6840°N, 114.4100°W.
How do I get to Guyer Hot Springs?
Guyer Hot Springs has Roadside road access, with the nearest road being Warm Springs Road (22 ft from the road).
Can I camp near Guyer Hot Springs?
Yes, North Fork (Id) is located nearby (7.3 miles away).
What minerals are in the water at Guyer Hot Springs?
Water chemistry analysis shows the presence of pH, Calcium, Magnesium, Sodium, Sulfate, Chloride. The pH is 9.1 (alkaline).
Is it safe to soak at Guyer Hot Springs?
The water at Guyer Hot Springs reaches 158°F, which can cause severe burns. Do not enter the source pool directly — look for cooled side pools or downstream areas where the water has cooled to a safe temperature. Access may be on private land or unconfirmed — verify current conditions before visiting. Always tell someone your plans before visiting remote hot springs.
Is Guyer Hot Springs crowded?
Guyer Hot Springs is accessible from a paved road, making it easy to reach. Weekends and holidays may be busier — consider visiting on a weekday for a quieter experience.
What should I bring to Guyer Hot Springs?
Essentials for Guyer Hot Springs: swimsuit, towel, water bottle, warm layers for before and after soaking, camping gear, a trash bag to pack out what you pack in. The water is over 110°F — test the temperature before entering and watch for scalding near the source.
