Loftus Hot Spring

Boise County, Idaho · Near Idaho City
43.7240°N, 115.6040°W · 3,630 ft
129°F 35°F air · Good soaking weather 3,630 ft Open Roadside US Forest Service Camping nearby (2.9 mi)

Loftus Hot Spring is a roadside thermal source within the Boise National Forest, thirteen or so miles out of Idaho City, Boise County, Idaho. Open to the public per the record. Hot water, hot enough that it needs cooling before anyone sits in it, and the 1981 sample shows it to be strongly alkaline. There is a campground a few miles along.

Location

Middle Fork Road runs right by, under a hundred feet from the water. Forest Service land, nothing special in the designation. The spring sits fairly low for Idaho mountain country, yet the snow comes down in quantity, something close to nine feet a winter, and the area gets a fair amount of rain through the year.

The record leans winter. Ninemeyer Campground is about three miles away. Test the water before you get in; at the recorded heat it will burn if you are careless. The water is notably alkaline. Chemistry dates to 1981. Nothing on file mentions a fee.

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 Loftus Hot Spring.

Aerial view of the ground around Loftus Hot Spring LiDAR bare-earth view of the same ground around Loftus 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.

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

That's about twice the US average of 65. It's higher than at 82% 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
30°
Jan
32°
Feb
38°
Mar
44°
Apr
54°
May
64°
Jun
75°
Jul
75°
Aug
64°
Sep
50°
Oct
37°
Nov
28°
Dec
Annual Precip: 28.8 in Annual Snow: 110.1 in
Best Time to Visit
December Air 28°F · Water 129°F · +101° contrast
January Air 30°F · Water 129°F · +100° contrast
February Air 32°F · Water 129°F · +97° contrast
December offers 47°F more contrast than July
Current Conditions
35°F
S 0.0 mph 93% Good soaking weather
Today 76° Low 48° Sunny
Spring is +53° warmer
Wednesday 82° Low 53° Sunny
Spring is +47° warmer
Thursday 74° Low 48° Showers And Thunderstorms Likely 73% precip
Spring is +55° warmer
Friday 74° Low 47° Mostly Sunny then Slight Chance Rain Showers 19% precip
Spring is +55° warmer
Saturday 77° Low 49° Sunny 5% precip
Spring is +52° warmer
Water Chemistry Sampled 1981-05-27

The water at Loftus Hot Spring is alkaline (pH 9.6).

pH 9.6 Alkaline
pH influences mineral absorption through skin
Calcium 2 mg/L
May support bone density and joint health
Sodium 42 mg/L
Supports circulation and skin hydration
Sulfate 21 mg/L
Traditionally used for skin conditions and inflammation
Chloride 11 mg/L
Natural antiseptic with skin health benefits
Where to Stay

Some links are affiliate links. We may earn a commission at no extra cost to you.

Nearby Camping
Ninemeyer Campground 2.9 mi away

Overview:Due to a wildfire, there are no amenities at the campground.  Currently there are no developed campfire rings therefore when Stage 1 fire restrictions area in effect, no fires are permitted.A stay at Ninemeyer Campground enables guests to enjoy all the beauty and recreation offered along the (Middle Fork Boise River Road) Forest Service (FS) Road 268. Weather is usually good from mid-May through late September and is easily accessible by car in good weather, although the road is some...

Reserve on Recreation.gov →
Temperature
129°F
Warm Hot Boiling
Water Temp 129°F (54°C)
Avg Air Temp 49°F
Above Ambient +80°F
Great soaking conditions September
Access
Open
Road Access Roadside
Nearest Road Middle Fork Road
Distance to Road 76 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 Loftus Hot Spring?
Loftus Hot Spring has a water temperature of 129°F (54°C). This is considered a hot spring, well above body temperature.
Where is Loftus Hot Spring located?
Loftus Hot Spring is located in Boise County, Idaho at 3,630 feet elevation, near Idaho City. Coordinates: 43.7240°N, 115.6040°W.
How do I get to Loftus Hot Spring?
Loftus Hot Spring has Roadside road access, with the nearest road being Middle Fork Road (76 ft from the road).
Is Loftus Hot Spring free to visit?
Loftus Hot Spring has Open access. It is managed by US Forest Service.
Can I camp near Loftus Hot Spring?
Yes, Ninemeyer Campground is located nearby (2.9 miles away).
What minerals are in the water at Loftus Hot Spring?
Water chemistry analysis shows the presence of pH, Calcium, Sodium, Sulfate, Chloride. The pH is 9.6 (alkaline).
Is it safe to soak at Loftus Hot Spring?
With care. At 129°F Loftus 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.