🌡️ Wind Chill & Heat Index Calculator
Switch between wind chill (cold) and heat index (hot) to get the real feels-like temperature with danger level, frostbite risk times, and heat illness thresholds.
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Frostbite Risk Time — Wind Chill Reference
| Temp (°C) | 10 km/h | 20 km/h | 40 km/h | 60 km/h | 80 km/h |
|---|
Risk of frostbite to exposed skin. "30 min" = frostbite possible within 30 minutes. Source: Environment Canada / NWS Wind Chill Chart.
Formulas Used
Wind Chill uses the North American / UK standard formula (Environment Canada / UK Met Office, 2001):
WC = 13.12 + 0.6215T − 11.37V0.16 + 0.3965T × V0.16
Where T = air temp (°C), V = wind speed (km/h). Valid for T ≤ 10°C and V ≥ 4.8 km/h.
Where T = air temp (°C), V = wind speed (km/h). Valid for T ≤ 10°C and V ≥ 4.8 km/h.
Heat Index uses the Rothfusz regression equation (NWS/NOAA):
HI = −42.379 + 2.04901523T + 10.14333127R − 0.22475541TR − 0.00683783T² − 0.05481717R² + 0.00122874T²R + 0.00085282TR² − 0.00000199T²R²
Where T = temp (°F), R = relative humidity (%)
Where T = temp (°F), R = relative humidity (%)
Heat index is only meaningful at temperatures above 27°C (80°F) and humidity above 40%. Wind chill is most relevant below 10°C (50°F) with wind speeds above 5 km/h.