At 169°F, the source water at Sunbeam 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:Custer County, ID, USA - panoramio (2).jpg — cc by-sa 3.0
Sunbeam Hot Springs runs at a scalding 169 degrees Fahrenheit directly beside the Salmon River Scenic Byway, making it one of Idaho's hottest roadside thermal features. The source water is dangerously hot, but it cools as it cascades over rocks toward the Salmon River, creating pools at varying temperatures.
At 6,160 feet in the Challis National Forest, the spring sends clouds of steam across the highway on cold mornings. The water emerges clear with an alkaline pH of 9.0 and carries little mineral load at 291 mg/L total dissolved solids. Where the thermal flow meets the cold Salmon River, visitors find the temperature gradient they need. The river canyon here is narrow and dramatic, with steep forested slopes rising from both banks. Annual snowfall reaches 125 inches, and air temperatures average just 40.2 degrees.
History of Sunbeam Hot Springs
Sunbeam sits on the Yankee Fork mining district's thermal corridor, where water circulates deep along the Sunbeam Fault before returning at temperatures confirming extreme geothermal gradient. USGS measurements recorded 76.5 degrees Celsius at the source. The 128.8-degree differential above ambient air is among the highest in Idaho. Early miners and settlers used these springs beginning in the 1870s when the area saw intensive gold and silver extraction.
The source water at 169 degrees causes severe burns on contact. Only soak where thermal water mixes with river water in naturally cooled pools at the river's edge. Pole Flat Campground sits 4.6 kilometers away with vault toilets, drinking water, and sites for vehicles up to 32 feet. The Scenic Byway provides year-round road access, though winter conditions can be icy. Arrive early on summer weekends.
Is Sunbeam Hot Springs worth visiting?
Best for
Observing powerful hot springs
Easy day trips
Overnight camping trips
Not ideal for
Casual soaking
Sunbeam Hot Springs is well suited for observing powerful hot springs and easy day trips.
Monthly Climate
22°Jan
24°Feb
30°Mar
35°Apr
44°May
55°Jun
66°Jul
65°Aug
55°Sep
40°Oct
28°Nov
19°Dec
Annual Precip: 23.9 inAnnual Snow: 125.0 in
Best Time to Visit
DecemberAir 19°F · Water 169°F · +150° contrast
JanuaryAir 22°F · Water 169°F · +147° contrast
FebruaryAir 24°F · Water 169°F · +145° contrast
December offers 47°F more contrast than July
USGS Field Measurements
Recent Temperature
169.7°F
(76.5°C)Measured Nov 02, 1983
Water ChemistrySampled 1983-11-02
The water at Sunbeam Hot Springs is alkaline (pH 9.0) with 291 mg/L total dissolved solids.
This campground is away from the main road and up the hill overlooking the river and the dredge ponds. Campsites include picnic tables tent pads fire rings with cooking grills. Campground amenities include a vault toilet and drinking water. Sites accommodate trailers and motorhomes up to 32 feet long.
What is the water temperature at Sunbeam Hot Springs?
Sunbeam Hot Springs has a water temperature of 169°F (76°C). This is considered a hot spring, well above body temperature.
Where is Sunbeam Hot Springs located?
Sunbeam Hot Springs is located in Custer County, Idaho at 6,160 feet elevation, near Challis. Coordinates: 44.2680°N, 114.7480°W.
How do I get to Sunbeam Hot Springs?
Sunbeam Hot Springs has Roadside road access, with the nearest road being Salmon River Scenic Byway (143 ft from the road).
Is Sunbeam Hot Springs free to visit?
Sunbeam Hot Springs has Open access. It is managed by US Forest Service.
Can I camp near Sunbeam Hot Springs?
Yes, Pole Flat Campground is located nearby (2.9 miles away).
What minerals are in the water at Sunbeam Hot Springs?
Water chemistry analysis shows the presence of pH, Total Dissolved Solids, Calcium, Magnesium, Sodium, Sulfate, Chloride, Iron. The pH is 9.0 (alkaline). Total dissolved solids measure 291 mg/L.
Is it safe to soak at Sunbeam Hot Springs?
The water at Sunbeam Hot Springs reaches 169°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. Always tell someone your plans before visiting remote hot springs.
Is Sunbeam Hot Springs crowded?
Sunbeam 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 Sunbeam Hot Springs?
Essentials for Sunbeam 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.
Temperature
169°F
WarmHotBoiling
Water Temp169°F (76°C)
Avg Air Temp40°F
Above Ambient+129°F
Perfect soaking weatherMarch
Access
Open
Road AccessRoadside
Nearest RoadSalmon River Scenic Byway
Distance to Road143 ft
Land
OwnershipFederal
AgencyUS Forest Service
DesignationNational Forest
UnitChallis National Forest
ManagerUS Forest Service
Protection3 - Protected, subject to extractive use
