Boulder Hot Springs

Jefferson County, Montana · Near Boulder
46.1980°N, 112.0940°W · 4,880 ft
169°F 35°F air · Good soaking weather 4,880 ft Short Walk Camping nearby (18.0 mi)
Very Hot Source, Use Extreme Caution

At 169°F, the source water at Boulder Hot Springs is hot enough to cause burns. Some hot springs this hot have cooler side pools or downstream areas suitable for soaking. Always test the water temperature before entering.

Water at Boulder Hot Springs arrives scalding, hot enough to blister skin, a few miles outside the town of Boulder in Jefferson County. Sitting in it straight from the source is out of the question until it cools. Ownership of the ground and the rules for using it are both missing. A 1976 USGS sample came back alkaline, carrying iron along with calcium, magnesium, sodium and sulfate.

Location

The spring sits a tenth of a mile from the nearest road, a short walk, at valley elevation close to town. Winters bring a moderate snowpack and the year is middling for rain. Being this close to Boulder, it is an easy drive, assuming access is allowed.

Do not touch the source. At this temperature the water scalds in seconds. Any soaking would need cooled water, and nothing on file says if that exists. Winter is the listed season, and the snow is manageable. Sheepshead Picnic Area is the closest camp, around eighteen miles out. Access is not recorded, so confirm before visiting.

Terrain

USGS hasn't flown a detailed laser scan here yet, so this view comes from aerial photos and older elevation data.

Aerial view of the ground around Boulder Hot Springs

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 southwest.
Highest ground nearby
344 ft above the spring
Within a quarter mile, to the southwest
Cross-section through the spring

A slice through the ground from west to east, about 0.6 miles end to end.

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

Heat Below
125 milliwatts per square meter of heat flow

That's about twice the US average of 65. It's higher than at 75% 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
20°
Feb
30°
Mar
38°
Apr
49°
May
58°
Jun
67°
Jul
67°
Aug
57°
Sep
42°
Oct
29°
Nov
19°
Dec
Annual Precip: 20.2 in Annual Snow: 57.5 in
Best Time to Visit
December Air 19°F · Water 169°F · +150° contrast
February Air 20°F · Water 169°F · +149° contrast
January Air 21°F · Water 169°F · +148° contrast
December offers 48°F more contrast than August
Current Conditions
35°F
NNW 0.0 mph 90% Good soaking weather
Today 67° Low 41° Sunny 1% precip
Spring is +102° warmer
Wednesday 65° Low 44° Mostly Sunny 2% precip
Spring is +104° warmer
Thursday 72° Low 48° Mostly Sunny then Chance Showers And Thunderstorms 35% precip
Spring is +97° warmer
Friday 66° Low 45° Rain Showers Likely 69% precip
Spring is +103° warmer
Saturday 69° Low 45° Chance Light Rain 26% precip
Spring is +100° warmer
Water Chemistry Sampled 1976-04-27

The water at Boulder Hot Springs is alkaline (pH 8.8).

pH 8.8 Alkaline
pH influences mineral absorption through skin
Calcium 2 mg/L
May support bone density and joint health
Magnesium 0 mg/L
Known for muscle relaxation and stress relief
Sodium 120 mg/L
Supports circulation and skin hydration
Sulfate 74 mg/L
Traditionally used for skin conditions and inflammation
Chloride 18 mg/L
Natural antiseptic with skin health benefits
Iron 20 µg/L
Iron-rich springs may support circulation
Where to Stay

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Nearby Camping
Sheepshead Picnic Area 18.0 mi away

Overview Sheepshead Pavilion is available for reservations for private gatherings from mid-June through Labor Day weekend. The pavilion will accommodate about 200 people. It includes picnic tables, barbecue grills and water. There is no electricity to the pavilion, if electricity is needed please bring a generator.  Fees are based on group size: $75 per day for groups 1-50 $125 per day for groups 51-100  $200 per day for groups 101-200 With a 2+ day reservation, overnight use may be granted,...

Reservable Yes
Reserve on Recreation.gov →
Temperature
169°F
Warm Hot Boiling
Water Temp 169°F (76°C)
Avg Air Temp 42°F
Above Ambient +128°F
Great soaking conditions September
Access
Road Access Short Walk
Distance to Road 0.1 mi
Frequently Asked Questions
What is the water temperature at Boulder Hot Springs?
Boulder Hot Springs has a water temperature of 169°F (76°C). This is considered a hot spring, well above body temperature.
Where is Boulder Hot Springs located?
Boulder Hot Springs is located in Jefferson County, Montana at 4,880 feet elevation, near Boulder. Coordinates: 46.1980°N, 112.0940°W.
How do I get to Boulder Hot Springs?
Boulder Hot Springs has Short Walk road access (0.1 mi from the road).
Can I camp near Boulder Hot Springs?
Yes, Sheepshead Picnic Area is located nearby (18.0 miles away).
What minerals are in the water at Boulder Hot Springs?
Water chemistry analysis shows the presence of pH, Calcium, Magnesium, Sodium, Sulfate, Chloride, Iron. The pH is 8.8 (alkaline).
Is it safe to soak at Boulder Hot Springs?
No, not at the source. The water at Boulder Hot Springs reaches 169°F, which can cause severe burns within seconds. Look for cooled side pools or downstream stretches, and test with a hand before anything else.
Sources: USGS NWIS