Sullivan Hot Springs

Custer County, Idaho · Near Challis
44.2540°N, 114.4430°W · 5,540 ft
106°F 37°F air · Good soaking weather 5,540 ft Roadside Camping nearby (14.1 mi)
Aerial view of the ground around Sullivan Hot Springs LiDAR bare-earth view of the same ground around Sullivan Hot Springs
Aerial LiDAR bare earth

Drag the handle to compare the two views. The orange dot marks the spring, in a frame about three quarters of a mile wide.

A roadside soak outside Challis in Custer County, Sullivan Hot Springs runs a bit above a hundred degrees. Land owner and access status are blank in the record, which matters because a roadside spring with no ownership on file could be private. The water is notably mineral-heavy, with iron on the list.

Location

Dry side of the state, under twenty inches of precipitation, with around ninety inches of snow in a normal winter and an annual average temperature in the low forties. Elevation is about 5,500 feet. A hundred-odd feet separate the water from the road, so walking is not a factor. Who owns the land is not recorded, and no road is named.

The record's best months run December through February. Pole Flat Campground, about fourteen miles off, is the closest camping. The reading dates to November 1983, a USGS sample. Water in the low hundreds is comfortable for most people, but check ownership before going; nothing in the record says this is public.

Terrain

Aircraft with laser scanners measured this ground to within inches. The scan strips out trees and buildings, leaving the bare shape of the land around Sullivan Hot Springs.

Setting
Canyon floor
Steep ground climbs away on both sides of the spring.
Highest ground nearby
342 ft above the spring
Within a quarter mile, to the east
Cross-section through the spring

A slice through the ground from south to north, about 0.6 miles end to end.

Elevation data: USGS 3D Elevation Program. Aerial imagery: USGS The National Map. Public domain.

Heat Below
151 milliwatts per square meter of heat flow

That's about 2½ times the US average of 65. It's higher than at 94% of the springs on this site.

Heat flow measures the warmth working its way up through the ground from deep inside the earth. Where it runs high, rain and snowmelt that seep down through cracks in the rock come back up hot.

Heat flow estimate: Stanford Thermal Earth Model (Aljubran & Horne, 2024), CC BY 4.0.

Monthly Climate
21°
Jan
23°
Feb
30°
Mar
37°
Apr
47°
May
58°
Jun
69°
Jul
68°
Aug
57°
Sep
43°
Oct
30°
Nov
19°
Dec
Annual Precip: 19.0 in Annual Snow: 88.8 in
Best Time to Visit
December Air 19°F · Water 106°F · +87° contrast
January Air 21°F · Water 106°F · +85° contrast
February Air 23°F · Water 106°F · +83° contrast
December offers 50°F more contrast than July
Current Conditions
37°F
Clear N 0.0 mph 70% Good soaking weather
Today 75° Low 41° Sunny
Spring is +31° warmer
Wednesday 78° Low 46° Sunny 8% precip
Spring is +28° warmer
Thursday 73° Low 43° Chance Light Rain then Showers And Thunderstorms 80% precip
Spring is +33° warmer
Friday 71° Low 42° Chance Light Rain 34% precip
Spring is +35° warmer
Saturday 75° Low 43° Sunny 10% precip
Spring is +31° warmer
Water Chemistry Sampled 1983-11-02

The water at Sullivan Hot Springs is neutral (pH 6.9) with 684 mg/L total dissolved solids.

pH 6.9 Neutral
pH influences mineral absorption through skin
Higher mineral concentration for therapeutic soaking
Calcium 48 mg/L
May support bone density and joint health
Magnesium 11 mg/L
Known for muscle relaxation and stress relief
Sodium 170 mg/L
Supports circulation and skin hydration
Sulfate 39 mg/L
Traditionally used for skin conditions and inflammation
Chloride 57 mg/L
Natural antiseptic with skin health benefits
Iron 50 µg/L
Iron-rich springs may support circulation
Nearby Camping
Nearby Camping
Pole Flat Campground 14.1 mi away

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.

Reserve on Recreation.gov →
Mile-High Advisory 5,540 ft

Sullivan Hot Springs sits at 5,540 feet above sea level, way above the mile-high mark. You may not feel the altitude strongly, but hot water still dehydrates you faster at elevation. UV is about 22% stronger than at sea level, so bring sunscreen and drink more water than you normally would.

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Temperature
106°F
Warm Hot Boiling
Water Temp 106°F (41°C)
Avg Air Temp 42°F
Above Ambient +64°F
Good soaking conditions September
Access
Road Access Roadside
Distance to Road 112 ft
Frequently Asked Questions
What is the water temperature at Sullivan Hot Springs?
Sullivan Hot Springs has a water temperature of 106°F (41°C). This is considered a hot spring, well above body temperature.
Where is Sullivan Hot Springs located?
Sullivan Hot Springs is located in Custer County, Idaho at 5,540 feet elevation, near Challis. Coordinates: 44.2540°N, 114.4430°W.
How do I get to Sullivan Hot Springs?
Sullivan Hot Springs has Roadside road access (112 ft from the road).
Can I camp near Sullivan Hot Springs?
Yes, Pole Flat Campground is located nearby (14.1 miles away).
What minerals are in the water at Sullivan Hot Springs?
Water chemistry analysis shows the presence of pH, Total Dissolved Solids, Calcium, Magnesium, Sodium, Sulfate, Chloride, Iron. The pH is 6.9 (neutral). Total dissolved solids measure 684 mg/L.
Sources: USGS NWIS