West Pass Hot Spring

Blaine County, Idaho · Near Sun Valley
43.9820°N, 114.4860°W · 6,795 ft
124°F 22°F air · Good soaking weather 6,795 ft Open Roadside US Forest Service Camping nearby (13.1 mi)
Aerial view of the ground around West Pass Hot Spring LiDAR bare-earth view of the same ground around West Pass 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.

West Pass Hot Spring is a roadside hot spring in Sawtooth National Forest, Blaine County, some twenty-two miles from Sun Valley. It is open to the public on the record. Water at the source is hot, more than a person can sit in without cooling, according to a reading from August 1980. Sulfate, chloride, sodium, magnesium and calcium were all found in the sample.

Location

The unnamed road passes within about sixty feet, so there is no walk. Close to seven thousand feet up, with national forest all around. Snow is heavy, well over a hundred inches most winters, and outside of that the climate is dry.

Winter gets the nod on record; at this altitude that means a lot of snow on the road in. The nearest listed camping is the Wood River Group Overnight Area, tent only, about thirteen miles away. Hot enough at the source to hurt, so test first. Access is open.

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 West Pass Hot Spring.

Setting
Hillside
The spring sits on a steep slope that climbs to the south.
Highest ground nearby
431 ft above the spring
Within a quarter mile, to the south
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
22°
Jan
22°
Feb
28°
Mar
33°
Apr
42°
May
52°
Jun
64°
Jul
63°
Aug
54°
Sep
39°
Oct
28°
Nov
19°
Dec
Annual Precip: 25.4 in Annual Snow: 134.3 in
Best Time to Visit
December Air 19°F · Water 124°F · +105° contrast
January Air 22°F · Water 124°F · +102° contrast
February Air 22°F · Water 124°F · +102° contrast
December offers 45°F more contrast than July
Current Conditions
22°F
N 0.0 mph 92% Good soaking weather
Today 65° Low 41° Sunny
Spring is +59° warmer
Wednesday 70° Low 46° Sunny 11% precip
Spring is +54° warmer
Thursday 63° Low 43° Light Rain Likely then Showers And Thunderstorms 84% precip
Spring is +61° warmer
Friday 64° Low 41° Chance Light Rain 29% precip
Spring is +60° warmer
Saturday 67° Low 42° Sunny 9% precip
Spring is +57° warmer
Water Chemistry Sampled 1980-08-07

The water at West Pass Hot Spring is slightly alkaline (pH 8.5).

pH 8.5 Slightly Alkaline
pH influences mineral absorption through skin
Calcium 20 mg/L
May support bone density and joint health
Magnesium 5 mg/L
Known for muscle relaxation and stress relief
Sodium 110 mg/L
Supports circulation and skin hydration
Sulfate 83 mg/L
Traditionally used for skin conditions and inflammation
Chloride 39 mg/L
Natural antiseptic with skin health benefits
Nearby Camping
Nearby Camping
Wood River Group Overnight Area (Tent Only) 13.1 mi away

Overview Wood River Group Overnight Area is located inside the Wood River Campground, which has 30 single campsites for RV's and tent camping, which are available for use on a first-come first-served basis. This campground is located on the banks of the beautiful Big Wood River at an elevation of 6400 feet. Ketchum, Idaho is conveniently close, only 10 miles south. Visitors enjoy fishing, tubing and exploring local trails.Recreation This site is part of the Sawtooth National Recreation Area,...

Reservable Yes
Reserve on Recreation.gov →
Mile-High Advisory 6,795 ft

West Pass Hot Spring sits at 6,795 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 27% stronger than at sea level, so bring sunscreen and drink more water than you normally would.

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Temperature
124°F
Warm Hot Boiling
Water Temp 124°F (51°C)
Avg Air Temp 39°F
Above Ambient +85°F
Great soaking conditions September
Access
Open
Road Access Roadside
Distance to Road 59 ft
Land
Ownership Federal
Agency US Forest Service
Designation National Forest
Unit Sawtooth National Forest
Manager US Forest Service
Protection 3 - Protected, subject to extractive use
Frequently Asked Questions
What is the water temperature at West Pass Hot Spring?
West Pass Hot Spring has a water temperature of 124°F (51°C). This is considered a hot spring, well above body temperature.
Where is West Pass Hot Spring located?
West Pass Hot Spring is located in Blaine County, Idaho at 6,795 feet elevation, near Sun Valley. Coordinates: 43.9820°N, 114.4860°W.
How do I get to West Pass Hot Spring?
West Pass Hot Spring has Roadside road access (59 ft from the road).
Is West Pass Hot Spring free to visit?
West Pass Hot Spring has Open access. It is managed by US Forest Service.
Can I camp near West Pass Hot Spring?
Yes, Wood River Group Overnight Area (Tent Only) is located nearby (13.1 miles away).
What minerals are in the water at West Pass Hot Spring?
Water chemistry analysis shows the presence of pH, Calcium, Magnesium, Sodium, Sulfate, Chloride. The pH is 8.5 (slightly alkaline).
Is it safe to soak at West Pass Hot Spring?
With care. At 124°F West Pass 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.
Sources: USGS NWIS