Heat Index Calculator
NOAA Rothfusz formula — calculates feels-like temperature from air temperature and relative humidity.
116.3°F
46.9°C
Danger
Heat Index (Feels Like)
Risk Levels
Below 80°FNormal
80–90°FCaution
91–103°FExtreme Caution
103–124°FDanger
125°F+Extreme Danger
NOAA Heat Index Calculator
The heat index (feels-like temperature) is calculated using the NOAA Rothfusz regression equation, which accounts for the combined effect of air temperature and relative humidity on the human body. At temperatures below 80°F, a simplified formula is used. Adjustment factors are applied for low humidity and for the 80–87°F range with high humidity. The result represents how hot it actually feels when humidity is factored in. All calculations run locally in your browser.
Private & free — this tool runs entirely in your browser.
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