Potosi Hot Springs

Madison County, Montana · Near Virginia City
45.5900°N, 111.8990°W · 6,069 ft
122°F 33°F air · Good soaking weather 6,069 ft Roadside Camping nearby (16.0 mi)

Beside Willow Meadow Road in Madison County, Montana, Potosi Hot Springs comes up hot, past comfortable soaking temperature at the source. Virginia City is about twenty miles away. A USGS sample from January 1977 found it alkaline with iron. Neither the landowner nor the access status is on record, so plan on asking.

Location
61 miles from Virginia City, MT

Fairly high country, with a wet year and a solid snowpack, around sixty-five inches in a normal winter. The spring is roadside, under sixty feet from Willow Meadow Road. No land unit appears on the record, and no designation either, which leaves the question of who you would ask.

Hot water, so test before you get in. Camping: Red Mountain, about sixteen miles away. Winter is the season on record, and the snow is on the heavy side, so a midwinter drive up Willow Meadow Road is not something to assume. The reading is from 1977. Access unknown.

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 Potosi Hot Springs.

Aerial view of the ground around Potosi Hot Springs LiDAR bare-earth view of the same ground around Potosi 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.

Setting
Hillside
The spring sits on a steep slope that climbs to the west.
Highest ground nearby
510 ft above the spring
Within a quarter mile, to the west
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
80 milliwatts per square meter of heat flow

That's close to the US average of 65. It's higher than at 15% 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
18°
Jan
18°
Feb
28°
Mar
35°
Apr
45°
May
55°
Jun
65°
Jul
64°
Aug
54°
Sep
39°
Oct
27°
Nov
17°
Dec
Annual Precip: 25.8 in Annual Snow: 64.5 in
Best Time to Visit
December Air 17°F · Water 122°F · +105° contrast
January Air 18°F · Water 122°F · +104° contrast
February Air 18°F · Water 122°F · +104° contrast
December offers 48°F more contrast than July
Current Conditions
33°F
Good soaking weather
Tuesday 64° Low 32° Sunny 1% precip
Spring is +58° warmer
Wednesday 62° Low 39° Sunny 5% precip
Spring is +60° warmer
Thursday 68° Low 43° Partly Sunny then Showers And Thunderstorms Likely 61% precip
Spring is +54° warmer
Friday 63° Low 47° Rain Showers 76% precip
Spring is +59° warmer
Saturday 66° Low 44° Slight Chance Light Rain 20% precip
Spring is +56° warmer
Water Chemistry Sampled 1977-01-15

The water at Potosi Hot Springs is slightly alkaline (pH 8.3).

pH 8.3 Slightly Alkaline
pH influences mineral absorption through skin
Calcium 10 mg/L
May support bone density and joint health
Magnesium 0 mg/L
Known for muscle relaxation and stress relief
Sodium 88 mg/L
Supports circulation and skin hydration
Sulfate 98 mg/L
Traditionally used for skin conditions and inflammation
Chloride 5 mg/L
Natural antiseptic with skin health benefits
Iron 60 µg/L
Iron-rich springs may support circulation
Where to Stay

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Nearby Camping
Red Mountain (Mt) 16.0 mi away

Overview The Dillon Field Office is unable to make reservations for you. Please call Recreation.gov (877-444-6777) to book a reservation or book online. Campsites are available for reservation for the Peak-Season times of May 1st through September 15th. From September 16th through April 30th, all sites are first-come-first-serve. Red Mountain Campground is adjacent to the lower Madison River and provides good access for camping, fishing and floating. The campground has 19 camp sites, 11 ava...

Reservable Yes
Reserve on Recreation.gov →
Mile-High Advisory 6,069 ft

Potosi Hot Springs sits at 6,069 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 24% stronger than at sea level, so bring sunscreen and drink more water than you normally would.

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Temperature
122°F
Warm Hot Boiling
Water Temp 122°F (50°C)
Avg Air Temp 39°F
Above Ambient +83°F
Great soaking conditions September
Access
Road Access Roadside
Nearest Road Willow Meadow Road
Distance to Road 56 ft
Frequently Asked Questions
What is the water temperature at Potosi Hot Springs?
Potosi Hot Springs has a water temperature of 122°F (50°C). This is considered a hot spring, well above body temperature.
Where is Potosi Hot Springs located?
Potosi Hot Springs is located in Madison County, Montana at 6,069 feet elevation, near Virginia City. Coordinates: 45.5900°N, 111.8990°W.
How do I get to Potosi Hot Springs?
Potosi Hot Springs has Roadside road access, with the nearest road being Willow Meadow Road (56 ft from the road).
Can I camp near Potosi Hot Springs?
Yes, Red Mountain (Mt) is located nearby (16.0 miles away).
What minerals are in the water at Potosi Hot Springs?
Water chemistry analysis shows the presence of pH, Calcium, Magnesium, Sodium, Sulfate, Chloride, Iron. The pH is 8.3 (slightly alkaline).
Is it safe to soak at Potosi Hot Springs?
With care. At 122°F Potosi Hot Springs 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