Rosalys Warm Spring

Blaine County, Idaho · Near Sun Valley
44.1010°N, 114.8650°W · 6,560 ft
106°F 24°F air · Good soaking weather 6,560 ft Short Walk Camping nearby (3.6 mi)
Aerial view of the ground around Rosalys Warm Spring LiDAR bare-earth view of the same ground around Rosalys Warm 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.

Rosalys Warm Spring is a Blaine County spring about thirty-nine miles from Sun Valley and a third of a mile from the nearest road. Despite the name, the water is above body heat, hot enough to feel like a bath. Land owner and access are not on record. Outlet Campground is a few miles away.

Location

High, around sixty-five hundred feet, with heavy snow, thirteen and a half feet across an average winter. The walk from the car is short. The road itself has no name in the record. Nothing is listed for a land unit or a designation, and the record is quiet on what the ground looks like.

Winter months are the listed best, though with that snowpack you need the road open. Outlet Campground, a few miles away, is the camping on file. No fee entry. The chemistry is from 1979. Check who owns the land and if you are allowed on it. The record says nothing either way.

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 Rosalys Warm Spring.

Setting
Hillside
The spring sits on a steep slope that climbs to the northwest.
Highest ground nearby
257 ft above the spring
Within a quarter mile, to the northwest
Cross-section through the spring

A slice through the ground from northwest to southeast, 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
23°
Feb
29°
Mar
34°
Apr
42°
May
52°
Jun
64°
Jul
63°
Aug
53°
Sep
39°
Oct
27°
Nov
19°
Dec
Annual Precip: 30.0 in Annual Snow: 161.7 in
Best Time to Visit
December Air 19°F · Water 106°F · +87° contrast
January Air 22°F · Water 106°F · +84° contrast
February Air 23°F · Water 106°F · +83° contrast
December offers 45°F more contrast than July
Current Conditions
24°F
S 12.1 mph 91% Good soaking weather
Today 69° Low 31° Sunny
Spring is +37° warmer
Wednesday 75° Low 36° Sunny 6% precip
Spring is +31° warmer
Thursday 69° Low 33° Chance Light Rain then Showers And Thunderstorms 83% precip
Spring is +37° warmer
Friday 68° Low 30° Mostly Sunny then Chance Light Rain 31% precip
Spring is +38° warmer
Saturday 71° Low 32° Sunny 9% precip
Spring is +35° warmer
Water Chemistry Sampled 1979-09-12

The water at Rosalys Warm Spring is alkaline (pH 9.4).

pH 9.4 Alkaline
pH influences mineral absorption through skin
Calcium 3 mg/L
May support bone density and joint health
Sodium 57 mg/L
Supports circulation and skin hydration
Sulfate 34 mg/L
Traditionally used for skin conditions and inflammation
Chloride 7 mg/L
Natural antiseptic with skin health benefits
Nearby Camping
Nearby Camping
Outlet Campground 3.6 mi away

Overview Outlet Campground is located next to beautiful Redfish Lake beneath the Sawtooth Mountain Range at an elevation of 6,500 feet. Recreation Outlet Campground is in the heart of the beautiful Sawtooth National Recreation Area, where outdoor activities abound. Redfish Lake offers excellent boating, water skiing, canoeing, kayaking and fishing for rainbow trout and Kokanee salmon. Little Redfish Lake is just down the road, offering additional fishing and canoeing. In the immediate are...

Reservable Yes
Reserve on Recreation.gov →
Mile-High Advisory 6,560 ft

Rosalys Warm Spring sits at 6,560 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 26% 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 39°F
Above Ambient +67°F
Great soaking conditions September
Access
Road Access Short Walk
Distance to Road 0.3 mi
Frequently Asked Questions
What is the water temperature at Rosalys Warm Spring?
Rosalys Warm Spring has a water temperature of 106°F (41°C). This is considered a hot spring, well above body temperature.
Where is Rosalys Warm Spring located?
Rosalys Warm Spring is located in Blaine County, Idaho at 6,560 feet elevation, near Sun Valley. Coordinates: 44.1010°N, 114.8650°W.
How do I get to Rosalys Warm Spring?
Rosalys Warm Spring has Short Walk road access (0.3 mi from the road).
Can I camp near Rosalys Warm Spring?
Yes, Outlet Campground is located nearby (3.6 miles away).
What minerals are in the water at Rosalys Warm Spring?
Water chemistry analysis shows the presence of pH, Calcium, Sodium, Sulfate, Chloride. The pH is 9.4 (alkaline).
Sources: USGS NWIS