Natural hot spring · Idaho
Mormon Ranch Warm Spring
Lemhi County, Idaho · 39 miles northwest of Challis, ID
Last updated
- Type
- Natural Natural hot spring
- Water temperature
- 117°F (47°C) at the source
- Cost
- Not recorded
- Hours or season
- Not recorded
- Clothing
- Not recorded
- Nearest town
- Challis, ID (39 mi / 62 km)
- Coordinates
- Pools or sources
- 1
- Very hot: above comfortable soaking temperature for most people. Enter slowly.
About Mormon Ranch Warm Spring
Mormon Ranch Warm Spring is a natural hot spring in Lemhi County, Idaho, about 39 miles northwest of Challis, ID. The nearest large city is Boise, ID, roughly 118 miles away as the crow flies.
The temperature at the source has been recorded at 117°F (47°C). That puts it in the "too hot to enter at the source" range. Water this hot can burn skin quickly. Soaking pools are usually cooled by mixing with creek or tap water. Never enter the source itself.
It is a natural spring with little or no development. Some natural springs have rock pools you can sit in, while others are too hot, too shallow or on land where soaking is not allowed.
Water temperature
Too hot to enter at the source. Water this hot can burn skin quickly. Soaking pools are usually cooled by mixing with creek or tap water. Never enter the source itself.
Readings come from the NOAA thermal springs list, USGS water quality samples, and other public sources. Temperatures change with season, flow and pool design. See our soak temperature guide for safe soaking times.
Map and directions
Red marks Mormon Ranch Warm Spring. Other colored dots are nearby springs in this directory. Coordinates: 44.95100, -114.70400.
Getting there
- Nearest town: Challis, ID. The spring is about 39 miles (62 km) northwest of town in a straight line.
- Nearest large city: Boise, ID, about 118 miles (190 km) in a straight line.
- Planning from a city? See hot springs near Missoula, MT.
- Use the directions buttons above for a driving route. Final roads to many springs are unpaved, seasonal or closed in winter, so check road conditions before you go.
Weather forecast
Live forecast for this exact spot from the US National Weather Service.
Hot springs near Mormon Ranch Warm Spring
- Snowshoe Johnsons Hot Spring 108°F
- Hospital Hot Spring 115°F
- Loon Creek Hot Spring 120°F
- Cox Hot Springs 131°F
- Foster Ranch Hot Springs 135°F
- Owen Cabin Hot Spring 133°F
Before you go
- Check the operator, land manager or park website for current hours, fees and closures. Details in any directory can go out of date.
- Pack out everything you bring, including food scraps. Do not use soap in natural pools.
- Keep your head above water. Warm fresh water can carry Naegleria fowleri, a rare but deadly amoeba that enters through the nose.
- Drink water, limit soaks to 10 to 20 minutes at a time in very hot water, and skip alcohol.
- Read our hot spring etiquette guide and safety guide.
Frequently asked questions
How hot is Mormon Ranch Warm Spring?
The temperature at the source has been recorded at 117°F (47°C), which is too hot to enter at the source. Water this hot can burn skin quickly. Soaking pools are usually cooled by mixing with creek or tap water. Never enter the source itself.
Where is Mormon Ranch Warm Spring?
Mormon Ranch Warm Spring is in Lemhi County, Idaho, about 39 miles northwest of Challis, ID. The GPS coordinates are 44.9510, -114.7040.
Can you soak at Mormon Ranch Warm Spring?
The source is too hot to enter safely. Natural springs vary. Some have pools built by visitors, others are too hot or shallow, and some are on private land or in areas where bathing is banned. Check local rules and test the water before you get in.
What hot springs are near Mormon Ranch Warm Spring?
The closest listed spring is Snowshoe Johnsons Hot Spring, about 7.6 miles northeast. Hospital Hot Spring is about 9 miles away.
What should I bring to a hot spring?
Water to drink, a towel, sandals with grip, a bag to pack out trash, and warm layers for after your soak. At primitive springs bring a headlamp and tell someone where you are going.
Sources and corrections
This listing combines the NOAA NCEI Thermal Springs List, the USGS/EPA Water Quality Portal. Data last refreshed August 2026. Source 1 Source 2
Visited recently? Send a correction, such as a temperature reading, fee, closure or photo. If you look after this spring and want it removed, see removal requests.