At 144°F, the source water at Straight Creek Hot Spring 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.
Straight Creek Hot Spring runs at 144 degrees Fahrenheit right alongside Middle Fork Road in the Boise National Forest, emerging 97.8 degrees above ambient air temperature. With a pH of 9.6, this is among the most alkaline thermal features in Idaho, indicating deep circulation through the granitic Idaho Batholith.
Just 68 feet from the road at 4,100 feet elevation in Boise County, the spring sends steam into the forest canopy along the Middle Fork of the Boise River corridor. The extremely low mineral content, with only 1.6 mg/L calcium and 1.8 mg/L chloride, produces water that feels almost unnaturally soft. Annual snowfall exceeds 10 feet, and the average air temperature holds at 46.2 degrees, creating substantial thermal contrast at the spring. USGS measurements confirmed 65 degrees Celsius, consistent with deep geothermal circulation.
History of Straight Creek Hot Spring
The Middle Fork Road corridor follows a fault zone through the Boise National Forest where multiple thermal features emerge. Straight Creek's exceptionally high pH and minimal mineral content indicate water that has spent extended time in contact with granitic rock at depth, dissolving silica while leaving behind heavier minerals. The Boise National Forest holds one of the highest concentrations of accessible hot springs in the American West, a product of the shallow heat source beneath central Idaho.
The spring sits right off Middle Fork Road near Idaho City, but the 144-degree source temperature causes severe burns. Do not enter the water at the source. Look downstream for areas where hot water has cooled or mixed with creek water. Barber Flat Cabin, a rentable 1935 CCC-built guard station, sits about five miles away for overnight stays. The road is typically passable from late May through October in a standard vehicle.
Is Straight Creek Hot Spring worth visiting?
Best for
Observing powerful hot springs
Easy day trips
Overnight camping trips
Not ideal for
Casual soaking
Straight Creek Hot Spring is well suited for observing powerful hot springs and easy day trips.
Monthly Climate
27°Jan
29°Feb
36°Mar
41°Apr
50°May
61°Jun
72°Jul
71°Aug
61°Sep
47°Oct
34°Nov
25°Dec
Annual Precip: 29.9 inAnnual Snow: 121.1 in
Best Time to Visit
DecemberAir 25°F · Water 144°F · +119° contrast
JanuaryAir 27°F · Water 144°F · +117° contrast
FebruaryAir 29°F · Water 144°F · +115° contrast
December offers 47°F more contrast than July
USGS Field Measurements
Recent Temperature
149.0°F
(65.0°C)Measured May 28, 1981
Water ChemistrySampled 1981-05-28
The water at Straight Creek Hot Spring is alkaline (pH 9.6).
Barber Flat Cabin (Boise National Forest, Id)5.2 mi away
Overview
The Barber Flat Cabin site was established for administrative use by the Forest Service in 1923, and was used prior to that by the Barber Lumber Company. At the time, the Forest Service used a cabin already on-site as a guard station and then built a new one in 1927. The current cabin and outbuildings were built by the Civilian Conservation Corps in 1935, and the cabin today looks much as it did back then.
Guests can drive to Barber Flat Cabin in two-wheel drive passenger cars or tr...
What is the water temperature at Straight Creek Hot Spring?
Straight Creek Hot Spring has a water temperature of 144°F (62°C). This is considered a hot spring, well above body temperature.
Where is Straight Creek Hot Spring located?
Straight Creek Hot Spring is located in Boise County, Idaho at 4,100 feet elevation, near Idaho City. Coordinates: 43.7880°N, 115.4440°W.
How do I get to Straight Creek Hot Spring?
Straight Creek Hot Spring has Roadside road access, with the nearest road being Middle Fork Road (68 ft from the road).
Is Straight Creek Hot Spring free to visit?
Straight Creek Hot Spring has Open access. It is managed by US Forest Service.
Can I camp near Straight Creek Hot Spring?
Yes, Barber Flat Cabin (Boise National Forest, Id) is located nearby (5.2 miles away).
What minerals are in the water at Straight Creek Hot Spring?
Water chemistry analysis shows the presence of pH, Calcium, Magnesium, Sodium, Sulfate, Chloride. The pH is 9.6 (alkaline).
Is it safe to soak at Straight Creek Hot Spring?
The water at Straight Creek Hot Spring reaches 144°F, which can cause severe burns. Do not enter the source pool directly — look for cooled side pools or downstream areas where the water has cooled to a safe temperature. Always tell someone your plans before visiting remote hot springs.
Is Straight Creek Hot Spring crowded?
Straight Creek Hot Spring is accessible from a paved road, making it easy to reach. Weekends and holidays may be busier — consider visiting on a weekday for a quieter experience.
What should I bring to Straight Creek Hot Spring?
Essentials for Straight Creek Hot Spring: swimsuit, towel, water bottle, camping gear, a trash bag to pack out what you pack in. The water is over 110°F — test the temperature before entering and watch for scalding near the source.
Temperature
144°F
WarmHotBoiling
Water Temp144°F (62°C)
Avg Air Temp46°F
Above Ambient+98°F
Perfect soaking weatherMarch
Access
Open
Road AccessRoadside
Nearest RoadMiddle Fork Road
Distance to Road68 ft
Land
OwnershipFederal
AgencyUS Forest Service
DesignationNational Forest
UnitBoise National Forest
ManagerUS Forest Service
Protection3 - Protected, subject to extractive use