Wind Chill vs Heat Index
**Wind chill** combines temperature and wind for cold exposure risk. **Heat index** combines temperature and humidity for heat stress—never use both at once; pick the formula for current conditions.
Step by step
1. Match the season
Below ~50°F with wind → wind chill; hot humid days → heat index.
2. Plan breaks
Extreme values trigger shorter outdoor exposure guidelines.
3. Layering vs hydration
Cold: wind blocks; heat: water and shade.
Wind chill vs heat index
Same site, different formulas—inputs must match weather mode.
- Wind chill: Cold + wind; frostbite timing.
- Heat index: Hot + humid; heat illness risk.
Use our calculators
Common mistakes
- Using heat index in winter
- Ignoring sun vs shade in heat
FAQ
What about moderate weather?
Neither index may apply—use actual temperature.