Historical reference · USGS/NOAA data
Find hot springs by water temperature
1,480 of America's 1,661 recorded natural thermal springs, sorted by how hot the water runs — from comfortable soaks to scalding vents best left for viewing. Built from public USGS data, with safety first.
Springs in the ideal soak range
Recorded between about 99°F and 104°F — the classic hot-tub window. Still verify access and current conditions before you go.
Scalding — for viewing, not soaking
Recorded above 113°F. Water this hot can burn in seconds; many are vents or geysers. Do not enter.
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How HotSpringIndex works
Frequently Asked Questions
Each spring is sorted into a water-temperature tier — Cool, Warm, Ideal, Hot, or Scalding — from the maximum surface temperature recorded in the USGS/NOAA thermal-springs inventory. "Ideal" means the classic hot-tub range up to about 104°F; "Scalding" (above 113°F) means the water can cause burns. It is a temperature classification, not a safety clearance.
No. The temperature is a single historical surface reading, not the temperature of a soaking pool, and it says nothing about ownership, access, footing, or current conditions. Many U.S. thermal springs are on private or protected land, undeveloped, or dangerous. Always verify legal access and safety with the land manager before visiting.
The dataset records the maximum surface temperature at the source, and many thermal springs are near-boiling vents, geysers, or fumaroles rather than soakable pools. Water at or above 113°F can cause serious burns in seconds — those springs are for viewing, not soaking.