This calculator is for demonstrative purposes only and does not replace official advisories or medical guidance.
Formula:
This tool uses the
National Weather Service (NOAA) regression formula for computing the Heat Index in Fahrenheit:
HI = c₁ + c₂T + c₃RH + c₄TRH + c₅T² + c₆RH² + c₇T²RH + c₈TRH² + c₉T²RH²
Where:
- T = Temperature (°F)
- RH = Relative Humidity (%)
Note:
The NOAA formula is only accurate when:
- Temperature is ≥ 80°F (≈27°C)
- Relative Humidity is ≥ 40%
If conditions are outside this range, the calculator assumes the heat index is approximately equal to the air temperature. In 2023, IMD launched an experimental Heat Index derived from the Heat Index equation used by NOAA.