NOAA Heat Index & Feels-Like Temperature Calculator
### Biometeorology & Occupational Health: The Physics of Heat Index The human body regulates internal core temperature primarily through the **evaporative cooling of sweat** from the.
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📐 Formula
💡 Practical Example
For example, on a summer day with an air temperature of 90.0°F (32.2°C) and 65.0% relative humidity: The Rothfusz equation yields a Heat Index of \(\mathbf{102.5^\circ\text{F (39.2}^\circ\text{C)}}\) with a dew point of 76.9°F, triggering the NOAA Extreme Caution / Early Danger advisory.
📖 About NOAA Heat Index & Feels-Like Temperature Calculator
Biometeorology & Occupational Health: The Physics of Heat Index
The human body regulates internal core temperature primarily through the evaporative cooling of sweat from the skin.
Why High Humidity Magnifies Heat Stress
When relative humidity is high, the ambient air is already saturated with water vapor, preventing sweat from evaporating into the air. Consequently, the body cannot shed heat, causing skin surface temperature and internal body heat to climb dangerously higher than the thermometer reads.
How to Use This Calculator
Enter your Air Temperature (e.g. 90.0 (or 32.2)), Temperature Unit — choose from Fahrenheit (°F), Celsius (°C), and Relative Humidity (RH %) (e.g. 65.0). Results update instantly as you type — adjust any value to compare scenarios.
The Formula
National Oceanic and Atmospheric Administration (NOAA) / Rothfusz full heat index multiple regression polynomial: = -42.379 + 2.04901523 T + 10.14333127 R - 0.22475541 T R - 6.83783 × 10^-3 T^2 - 5.481717 × 10^-2 R^2 + 1.22874 × 10^-3 T^2 R + 8.5282 × 10^-4 T R^2 - 1.99 × 10^-6 T^2 R^2 T = Air Temperature (^), R = Relative Humidity (\%) Point (Magnus-Tetens): T_dew = (237.7 × α) / (17.27 - α), α = (17.27 T_c) / (237.7 + T_c) + ((RH) / (100))
Worked Example
For example, on a summer day with an air temperature of 90.0°F (32.2°C) and 65.0% relative humidity: The Rothfusz equation yields a Heat Index of 102.5^ (39.2^) with a dew point of 76.9°F, triggering the NOAA Extreme Caution / Early Danger advisory.
Understanding Your Result
Evaluate your result in the context of your specific use case and relevant industry standards or reference values. A single calculated result is a starting point — test two to three scenarios to understand how sensitive the outcome is to your key input assumptions. For high-stakes decisions, verify your result against a secondary source or subject-matter expert before acting.
💡 Methodological Standards & Calculation Accuracy
- All calculations are performed client-side in your browser using verified, standards-compliant mathematical algorithms.
- Results are provided for educational and informational analysis; verify critical applications with certified domain specialists.
- Ensure input values are entered in consistent units matching the selector options to guarantee accurate outputs.
- Periodic recalibration is recommended whenever baseline assumptions, operating parameters, or external conditions change.
Results are for informational and educational purposes only. Always verify critical decisions with a qualified professional.