Disclaimer

Last updated: September 2026. Please read this page carefully before using our calculators.

Educational information only

All content on WindChill — calculators, articles, tables, and examples — is published for general educational purposes. It is not apparent temperatures advice and is not a substitute for a qualified professional. We are not official NWS forecasts and heat-safety guidances, and no client or advisory relationship is created by your use of this Site.

The formulas here are the National Weather Service's published approximations with stated validity ranges (wind chill: ≤50°F and >3 mph; heat index: ≥80°F and ≥40% RH). Outside those ranges the concepts are undefined, not merely inaccurate.

Apparent temperatures are skin-heat-loss indices — they affect living tissue only. Pipes freeze, engines fail, and plants die at actual temperatures; dress and plan for the real number, protected for the felt one.

Accuracy of calculations

We implement well-known, publicly documented formulas (see the methodology section on each calculator page and NWS (NOAA) published formulas as applicable). Even correctly implemented formulas produce estimates that depend on your inputs and assumptions. Real-world outcomes vary. Do not rely on a single web tool for a consequential decision.

Advertising disclosure

WindChill is funded by display advertising served through Google AdSense. Advertisers have no influence over our content, formulas, or editorial choices, and placement of an ad is not an endorsement.

Errors and corrections

If you spot an error, please email hello@windchill.app with the inputs you used. Verified corrections are published promptly.