Sacajawea Hot Springs

Boise County, Idaho · Near Idaho City
44.1600°N, 115.1770°W · 5,000 ft
153°F 33°F air · Good soaking weather 5,000 ft Open Roadside US Forest Service Camping nearby (6.7 mi)
Very Hot Source, Use Extreme Caution

At 153°F, the source water at Sacajawea 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.

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

Sacajawea Hot Springs is scalding at the source. The water would burn you in seconds. It sits at the roadside in Boise National Forest, Boise County, a short way off Grandjean Road and about forty miles from Idaho City. Access is recorded as open, and Bonneville campground sits seven miles off.

Location

Five thousand feet up in heavy snow country. Fifteen feet most winters, and wet the rest of the year. Grandjean Road passes within a few dozen yards of the source, and once the road is open you can step from the car to the water. Forest Service land with the ordinary National Forest designation. No water chemistry is on file for it.

The best season on record is winter. At this temperature the source itself is off limits to skin. Any soaking happens only where the hot water has mixed with cold, and you test that first every time. Bonneville is the listed campground. No fee shows up. Snow load means checking Grandjean Road before you go.

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 Sacajawea Hot Springs.

Setting
Canyon floor
Steep ground climbs away on both sides of the spring.
Highest ground nearby
1,019 ft above the spring
Within a quarter mile, to the north
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
138 milliwatts per square meter of heat flow

That's about twice the US average of 65. It's higher than at 88% 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
26°
Jan
27°
Feb
33°
Mar
38°
Apr
45°
May
56°
Jun
68°
Jul
67°
Aug
57°
Sep
43°
Oct
31°
Nov
23°
Dec
Annual Precip: 34.1 in Annual Snow: 184.6 in
Best Time to Visit
December Air 23°F · Water 153°F · +130° contrast
January Air 26°F · Water 153°F · +127° contrast
February Air 27°F · Water 153°F · +126° contrast
December offers 45°F more contrast than July
Current Conditions
33°F
SSE 0.0 mph 97% Good soaking weather
Today 68° Low 46° Sunny
Spring is +85° warmer
Wednesday 75° Low 50° Sunny
Spring is +78° warmer
Thursday 67° Low 47° Showers And Thunderstorms 83% precip
Spring is +86° warmer
Friday 66° Low 45° Chance Rain Showers 34% precip
Spring is +87° warmer
Saturday 70° Low 46° Sunny 8% precip
Spring is +83° warmer
Nearby Camping
Nearby Camping
Bonneville 6.7 mi away

Overview Bonneville Campground is 19 miles east of Lowman, Idaho just off Highway 21 at an elevation of 4,700 feet. Warm Springs Creek runs alongside the campground and the South Fork Payette River lies across the highway. Visitors enjoy soaking at Bonneville Hot Springs a short distance above the campground, and fishing in the creek and river.Recreation A 1/4-mile hiking trail leads from the campground to Bonneville Hot Springs, where a soaking pool awaits. Warm Springs Creek offers good tro...

Reservable Yes
Reserve on Recreation.gov →
Temperature
153°F
Warm Hot Boiling
Water Temp 153°F (67°C)
Avg Air Temp 43°F
Above Ambient +110°F
Great soaking conditions September
Access
Open
Road Access Roadside
Nearest Road Grandjean Road
Distance to Road 135 ft
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 Sacajawea Hot Springs?
Sacajawea Hot Springs has a water temperature of 153°F (67°C). This is considered a hot spring, well above body temperature.
Where is Sacajawea Hot Springs located?
Sacajawea Hot Springs is located in Boise County, Idaho at 5,000 feet elevation, near Idaho City. Coordinates: 44.1600°N, 115.1770°W.
How do I get to Sacajawea Hot Springs?
Sacajawea Hot Springs has Roadside road access, with the nearest road being Grandjean Road (135 ft from the road).
Is Sacajawea Hot Springs free to visit?
Sacajawea Hot Springs has Open access. It is managed by US Forest Service.
Can I camp near Sacajawea Hot Springs?
Yes, Bonneville is located nearby (6.7 miles away).
Is it safe to soak at Sacajawea Hot Springs?
No, not at the source. The water at Sacajawea Hot Springs reaches 153°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