Back to calculator
Everyday LifeGenerated accuracy model review: 2026-05-06
Heat Index accuracy and testing
This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.
Formula source
- The calculator uses the Rothfusz regression equation used by the **National Weather Service (NWS)**. This complex formula approximates the heat index for temperatures of 80°F or higher and humidity of 40% or more.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Air Temperature: 90 °F
- Relative Humidity: 60%
Expected outputs
- Heat Index: 100 °F
- Danger Level: Extreme Caution
Known limitations
- This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
- Use the result as a planning estimate unless the calculator page states a stricter purpose.
Assumptions
- The formula is most reliable at 80°F or higher and humidity of 40% or more.
- Shade is assumed; direct sunlight can make conditions feel hotter.
- This is a weather safety estimate, not a medical diagnosis.
Unit handling
- Air Temperature accepts values in °F.
- Relative Humidity accepts values in %.
- Heat Index is displayed in °F.
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current heat-index-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Heat Index.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.