How to use the heat stroke criteria check
Enter a measured core body temperature and say whether persistent severe neurologic signs are present. The page tests the two heat stroke criteria separately and reports how many of them are met. Temperature can be entered in Fahrenheit or Celsius and the conversion is handled in code, with both units printed in the result. No heat index and no staged score is produced.
The criteria applied are a core temperature above 104 °F (40.0 °C) together with persistent severe neurologic signs such as confusion, seizure or reduced consciousness. Heat exhaustion is described as running below 104 °F with the person usually alert. Sources differ between 103 °F and 104 °F, so this page uses 104 °F and says so. The underlying material is a secondary source and the page is current as of October 2026.
When the criteria are met, the source describes calling for emergency help and beginning aggressive cooling at the same time, which is why both appear together in the result. When they are not met, that is not clearance: heat exhaustion can progress quickly to heat stroke and the two are hard to separate without an accurate measurement. Heat cramps are not covered because the available material is not solid enough, and sweating is shown as background rather than as a criterion. Central nervous system dysfunction is the key sign of heat stroke (CDC/NIOSH), so if confusion, slurred speech, seizure or loss of consciousness is present the page tells you to call 911 even when the temperature is below 104 °F or was not measured. This page is not a medical diagnosis. If awareness changes or the temperature keeps climbing, call 911 immediately.
Frequently asked questions
Sources differ between 103 °F and 104 °F. This page calculates with a core temperature above 104 °F, which is 40.0 °C. If the reading falls between the two values, the answer depends on which threshold is applied.
No. Classic heat stroke in an inactive person is described as occurring without sweating, but in exertional heat stroke continued sweating is very common. Sweating is therefore shown only as background and is not part of the criteria.
A negative result here is not clearance. Heat exhaustion is described as able to progress quickly to heat stroke, and the two are hard to tell apart without an accurate measurement. If symptoms persist or worsen, get medical care without delay.