Physics

Heat Index Calculator

Find the 'feels like' temperature from heat and humidity.

Calculated Output

Heat index (°F) 105.92

Heat index (°C) 41.068

Formula: Rothfusz regression (valid above ~80 °F)

Step-by-Step Breakdown

1. Values used:

2. Temperature = 90 °F

3. Relative humidity = 70 %

5. Heat index = 105.92°F

6. Heat index = 41.068°C

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The math behind it

Uses the NWS Rothfusz regression (most accurate above ~80 °F / 27 °C).

90 °F at 70% RH → ~106 °F.

Why does humidity matter?

High humidity slows sweat evaporation, so you feel hotter.