At 185°F, the source water at Bonneville 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.
Bonneville Hot Springs pushes 185-degree Fahrenheit water from the earth in the Boise National Forest, feeding constructed soaking pools a quarter mile downhill at Bonneville Campground. USGS data records the source at 88 degrees Celsius with a pH of 9.3, among the hottest and most alkaline springs in the state. The campground-to-spring trail makes this a rare walk-in soaking experience.
The spring emerges at 4,880 feet elevation on a forested slope above Warm Springs Creek in Boise County. The trail from Bonneville Campground climbs through mixed conifer forest, with the sound of the creek below. Annual snowfall exceeds 176 inches, burying the area in winter but feeding lush summer vegetation. The soaking pools are rock-and-log constructions where the superheated source water has cooled enough for bathing. Steam rises through the trees on cool mornings.
History of Bonneville Hot Springs
Bonneville Hot Springs sits along the same fault system that produces several other thermal features between Lowman and Idaho City. The water chemistry, with 77 mg/L sodium and negligible calcium and magnesium, mirrors the deep granitic circulation pattern seen throughout the Idaho Batholith. Sulfate levels at 50 mg/L are higher than neighboring springs, suggesting the water passes through a zone of sulfide mineralization before reaching the surface.
Bonneville Campground, 19 miles east of Lowman off Highway 21, is reservable and sits just a third of a mile from the springs. The quarter-mile trail gains modest elevation. Source water is dangerously hot, so soak only in downstream pools where temperatures have dropped to comfortable levels. Warm Springs Creek nearby offers trout fishing. Winter access depends on road conditions along Highway 21.
Is Bonneville Hot Springs worth visiting?
Best for
Observing powerful hot springs
Overnight camping trips
Not ideal for
Casual soaking
Bonneville Hot Springs is well suited for observing powerful hot springs and overnight camping trips.
Monthly Climate
27°Jan
29°Feb
35°Mar
39°Apr
47°May
58°Jun
70°Jul
69°Aug
59°Sep
45°Oct
32°Nov
24°Dec
Annual Precip: 33.8 inAnnual Snow: 176.2 in
Best Time to Visit
DecemberAir 24°F · Water 185°F · +161° contrast
JanuaryAir 27°F · Water 185°F · +158° contrast
FebruaryAir 29°F · Water 185°F · +156° contrast
December offers 46°F more contrast than July
USGS Field Measurements
Recent Temperature
190.4°F
(88.0°C)Measured Oct 26, 1992
Water ChemistrySampled 1979-03-13
The water at Bonneville Hot Springs is alkaline (pH 9.3).
Overview
Bonneville Campground is 19 miles east of Lowman, Idaho just off Highway 21 at an elevation of 4,700 feet. Warm Springs Creek runs alongside the campground and the South Fork Payette River lies across the highway. Visitors enjoy soaking at Bonneville Hot Springs a short distance above the campground, and fishing in the creek and river.Recreation
A 1/4-mile hiking trail leads from the campground to Bonneville Hot Springs, where a soaking pool awaits. Warm Springs Creek offers good tro...
What is the water temperature at Bonneville Hot Springs?
Bonneville Hot Springs has a water temperature of 185°F (85°C). This is considered a hot spring, well above body temperature.
Where is Bonneville Hot Springs located?
Bonneville Hot Springs is located in Boise County, Idaho at 4,880 feet elevation, near Idaho City. Coordinates: 44.1570°N, 115.3140°W.
How do I get to Bonneville Hot Springs?
Bonneville Hot Springs has Short Walk road access, with the nearest road being Bonneville Trailhead Road (0.3 mi from the road).
Is Bonneville Hot Springs free to visit?
Bonneville Hot Springs has Open access. It is managed by US Forest Service.
Can I camp near Bonneville Hot Springs?
Yes, Bonneville is located nearby (0.4 miles away).
What minerals are in the water at Bonneville Hot Springs?
Water chemistry analysis shows the presence of pH, Calcium, Magnesium, Sodium, Sulfate, Chloride. The pH is 9.3 (alkaline).
Is it safe to soak at Bonneville Hot Springs?
The water at Bonneville Hot Springs reaches 185°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 Bonneville Hot Springs crowded?
Bonneville Hot Springs sees varying levels of visitors depending on the season and day of the week.
What should I bring to Bonneville Hot Springs?
Essentials for Bonneville 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
185°F
WarmHotBoiling
Water Temp185°F (85°C)
Avg Air Temp45°F
Above Ambient+140°F
Perfect soaking weatherMarch
Access
Open
Road AccessShort Walk
Nearest RoadBonneville Trailhead Road
Distance to Road0.3 mi
Land
OwnershipFederal
AgencyUS Forest Service
DesignationNational Forest
UnitBoise National Forest
ManagerUS Forest Service
Protection3 - Protected, subject to extractive use