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Heat Index Calculator

Estimate apparent heat from air temperature and relative humidity.

°F
%
Heat index
102.7 °F
Extreme caution
Temperature90 °F
Relative humidity65%
Feels like39.3 °C

Heat index is an approximate shaded-air estimate; direct sun can increase perceived heat. Seek local heat-safety guidance.

About the Heat Index Calculator

Estimate apparent heat from air temperature and relative humidity.

It runs entirely in your browser — nothing you type is sent to a server — and the result updates as you edit the inputs. Estimates are for educational and informational purposes only; see ourdisclaimer.

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