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HotSpringIndex

About HotSpringIndex

U.S. hot springs by water temperature — the comfortable soaks, the scalding ones to avoid, and where to stay.

What we do

HotSpringIndex sorts every natural thermal spring in the USGS/NOAA inventory by its recorded water temperature — so travelers can tell a comfortable soak from a scalding vent before they plan a trip — while framing the data safety-first, because a temperature reading is not a safety clearance.

We focus on U.S. natural hot springs: water-temperature classification, locations, and safety. Every page on hotspringindex.org is built from the USGS/NOAA Thermal Springs List for the United States, cited and linkable so readers can trace any number back to its source.

Who runs this

HotSpringIndex is built and maintained by the HotSpringIndex Editorial Team. We're a small group working on making public U.S. natural hot springs: water-temperature classification, locations, and safety data easier for non-specialists to read. If you have a correction, a data tip, or a question about how a number was derived, the contact email below reaches us directly.

Who this is for

HotSpringIndex is built for hot-springs travelers, soakers, road-trippers, and outdoor enthusiasts planning where to go.

Why this exists

Public data on U.S. natural hot springs: water-temperature classification, locations, and safety is technically free, but practically locked behind file formats, acronyms, and paywalled dashboards. HotSpringIndexexists to close that gap: take the raw federal and public-sector data, and turn it into pages a normal person can read in thirty seconds.

How we work

  • Primary source only. We pull from the USGS/NOAA Thermal Springs List for the United States and cite the exact dataset and version on every page.
  • No invented numbers. If a figure is not in the underlying public data, it does not appear on hotspringindex.org. We never generate synthetic statistics to fill gaps.
  • Methodology, in plain English. We classify each spring from the maximum surface temperature in the USGS/NOAA Thermal Springs List into five water-temperature tiers: Cool (below 86°F/30°C), Warm (86–99°F), Ideal (99–104°F — the classic hot-tub range, capped at the CDC/CPSC safe limit), Hot (104–113°F — above the safe limit, burn risk), and Scalding (above 113°F/45°C — dangerous, often a vent or geyser). Springs with no recorded temperature are shown as “temperature not recorded” and never assigned a tier.
  • Refreshed on a schedule. The underlying USGS/NOAA inventory is a historical reference dataset (compiled 1965–1980) that is rarely revised; we refresh when the source is updated.
  • Corrections welcome. Readers flag issues all the time. When the source fixes a record, HotSpringIndex follows.

How our content is produced

HotSpringIndex is produced by our editorial team. Every spring’s classification is computed from public USGS/NOAA records and presented with its data source. We describe springs from documented measurements and cited sources rather than claiming personal visits.

Known limitations

The recorded figure is a maximum SURFACE temperature, not a soaking-pool temperature, and it is historical — real temperatures vary by season, rainfall, and location. The data carries no access, ownership, or developed-vs-primitive information; many springs are on private, tribal, or protected land, undeveloped, or dangerous. A tier is a temperature classification, NOT a safety clearance or a recommendation to enter. Hot-spring water can scald; always verify legal access and current conditions with the land manager, test the water yourself, and follow Leave No Trace.

Independence

HotSpringIndex is an independent publication. We are not funded, owned, or directed by any of the agencies, companies, or organizations that appear in our data. The site is free to read and carries no display advertising — see our Privacy Policy for how data is handled — and we do not take paid placements, sponsored rankings, or “remove-my-entry” fees.

Editorial standards

We hold every page to a stated, repeatable process rather than asking readers to take our word for it. How our content is produced and the standards behind it are documented in our Editorial Policy; how we verify figures before publishing is in our Fact-Checking Policy; and how we handle mistakes is in our Corrections Policy.

History

HotSpringIndex launched in 2026 as part of a small portfolio of independent public-data sites. It has been maintained and updated continuously since.

Contact

Tips, corrections, data-partnership questions, and press inquiries: hello@hotspringindex.org. More options on our contact page.