The thermometer lies about how it feels. Wind makes the cold bite harder and humidity makes the heat smother — apparent temperature tells the real story.
Wind Chill & Heat IndexLive
what it really feels like
Apparent temperature
-13°C
actual air temperature -5 °C
Controls
Presets
The thermometer only tells half the story. In the cold, wind strips away the thin warm layer around your skin, making it feel far colder — wind chill. In the heat, humidity blocks sweat from evaporating, making it feel hotter — the heat index. Both estimate the apparent temperature your body actually experiences.
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How it works
In the cold, wind sweeps away the thin insulating layer of warm air at your skin, so it feels far colder — the wind chill. In the heat, high humidity stops sweat from evaporating, so it feels hotter — the heat index. Both combine temperature with wind or humidity into the apparent temperature your body actually experiences, and both carry real health risks.
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The math, the assumptions, real-world uses, or a code translation — explained for this exact simulation.
Is this wind chill heat index calculator tool really free?▾
Yes. Wind Chill & Heat Index runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?▾
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?▾
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?▾
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.