Hospital Hot Spring

Custer County, Idaho · Near Challis
44.8360°N, 114.7900°W · 4,000 ft
115°F 34°F air · Good soaking weather 4,000 ft Open Hike US Forest Service Camping nearby (18.6 mi)
Aerial view of the ground around Hospital Hot Spring LiDAR bare-earth view of the same ground around Hospital Hot Spring
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.

Hospital Hot Spring is a backcountry source on Forest Service land in Custer County, Idaho, part of the Boise National Forest and a long way from anything. Challis is the nearest town listed, nearly thirty-six miles off. Public access is listed as open. The water runs hot, beyond what most people would sit in straight from the ground, and a 1980 sample found fairly low dissolved solids with some iron in it.

Location

Reaching the source means a hike of about two miles from a road the record leaves unnamed. National Forest land with no wilderness or other special designation noted. The elevation is modest for central Idaho. Snow is another matter, over eight feet in a typical year. Summers are on the dry side.

Winter is the recorded best season, deep snow or no. Yellowjacket Guard Station is the one campground on file, close to nineteen miles away. Hot enough to burn with prolonged contact, so test it first. The chemistry sample dates from 1980, and with no road named, the hike in is yours to navigate.

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 Hospital Hot Spring.

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

A slice through the ground from southwest to northeast, about 0.6 miles end to end.

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

Heat Below
115 milliwatts per square meter of heat flow

That's about twice the US average of 65. It's higher than at 67% 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
28°
Jan
30°
Feb
36°
Mar
42°
Apr
51°
May
61°
Jun
73°
Jul
72°
Aug
62°
Sep
46°
Oct
33°
Nov
25°
Dec
Annual Precip: 22.5 in Annual Snow: 101.9 in
Best Time to Visit
December Air 25°F · Water 115°F · +91° contrast
January Air 28°F · Water 115°F · +87° contrast
February Air 30°F · Water 115°F · +86° contrast
December offers 49°F more contrast than July
Current Conditions
34°F
Clear N 0.0 mph 86% Good soaking weather
Today 75° Low 46° Sunny
Spring is +40° warmer
Wednesday 80° Low 50° Sunny
Spring is +35° warmer
Thursday 76° Low 49° Rain Showers 80% precip
Spring is +39° warmer
Friday 73° Low 46° Chance Rain Showers 53% precip
Spring is +42° warmer
Saturday 76° Low 47° Sunny 10% precip
Spring is +39° warmer
Water Chemistry Sampled 1980-06-29

The water at Hospital Hot Spring is alkaline (pH 8.9) with 278 mg/L total dissolved solids.

pH 8.9 Alkaline
pH influences mineral absorption through skin
Higher mineral concentration for therapeutic soaking
Calcium 3 mg/L
May support bone density and joint health
Magnesium 0 mg/L
Known for muscle relaxation and stress relief
Sodium 90 mg/L
Supports circulation and skin hydration
Sulfate 41 mg/L
Traditionally used for skin conditions and inflammation
Chloride 14 mg/L
Natural antiseptic with skin health benefits
Iron 0 µg/L
Iron-rich springs may support circulation
Nearby Camping
Nearby Camping
Yellowjacket Guard Station 18.6 mi away

Overview Yellowjacket Guard Station is a historic Forest Service Ranger Station and Work Center. Originally constructed in 1925 and remodeled in 1934 by the Civilian Conservation Corps, the structure is eligible for listing on the National Register of Historic Places. Recreation Hikers, horseback riders, mountain bikers and off-road enthusiasts will find many trails in the surrounding area. Hunting is also a popular activity. Click here for an Idaho OHV safety messageFacilities The spacious...

Reservable Yes
Reserve on Recreation.gov →
Temperature
115°F
Warm Hot Boiling
Water Temp 115°F (46°C)
Avg Air Temp 47°F
Above Ambient +69°F
Great soaking conditions September
Access
Open
Road Access Hike
Distance to Road 2.1 mi
Land
Ownership Federal
Agency US Forest Service
Designation National Forest
Unit Boise National Forest
Manager US Forest Service
Protection 3 - Protected, subject to extractive use
Frequently Asked Questions
What is the water temperature at Hospital Hot Spring?
Hospital Hot Spring has a water temperature of 115°F (46°C). This is considered a hot spring, well above body temperature.
Where is Hospital Hot Spring located?
Hospital Hot Spring is located in Custer County, Idaho at 4,000 feet elevation, near Challis. Coordinates: 44.8360°N, 114.7900°W.
How do I get to Hospital Hot Spring?
Hospital Hot Spring has Hike road access (2.1 mi from the road).
Is Hospital Hot Spring free to visit?
Hospital Hot Spring has Open access. It is managed by US Forest Service.
Can I camp near Hospital Hot Spring?
Yes, Yellowjacket Guard Station is located nearby (18.6 miles away).
What minerals are in the water at Hospital Hot Spring?
Water chemistry analysis shows the presence of pH, Total Dissolved Solids, Calcium, Magnesium, Sodium, Sulfate, Chloride, Iron. The pH is 8.9 (alkaline). Total dissolved solids measure 278 mg/L.
Is it safe to soak at Hospital Hot Spring?
With care. At 115°F Hospital Hot Spring is hot enough to need short sessions, fifteen to twenty minutes, and plenty of water. Enter slowly and get out if you feel light-headed.