Calculate how cold it feels based on air temperature and wind speed. Determine wind chill temperature with frostbite exposure time estimates using the National Weather Service formula.
Wind chill is the perceived decrease in air temperature felt by the body on exposed skin due to the flow of air. Wind chill temperature is not the actual air temperature but represents how cold it feels when wind and cold air combine to remove heat from your body.
The faster the wind speed, the more rapidly heat is removed from your body, making you feel colder than the actual air temperature. Understanding wind chill is crucial for outdoor safety in cold weather conditions.
Where: WC = Wind Chill Temperature (°F), T = Air Temperature (°F), V = Wind Speed (mph)
Where: WC = Wind Chill Temperature (°C), T = Air Temperature (°C), V = Wind Speed (km/h)
| Wind Chill (°F) | Frostbite Time | Risk Level | Safety Recommendations |
|---|---|---|---|
| Above 16°F | No risk | Low | Dress appropriately for weather |
| 0°F to 16°F | 30+ minutes | Low | Dress warmly, limit time outdoors |
| -18°F to 0°F | 10-30 minutes | Moderate | Protect exposed skin, limit outdoor time |
| -35°F to -18°F | 5-10 minutes | High | Cover all exposed skin, avoid prolonged exposure |
| -60°F to -35°F | 2-5 minutes | Very High | Exposed skin freezes quickly, avoid outdoor activity |
| Below -60°F | Under 2 minutes | Extreme | Life-threatening conditions, stay indoors |
Convection: The primary mechanism behind wind chill. Moving air removes the thin layer of warm air that surrounds your body, allowing cooler air to replace it and increasing heat loss.
Evaporation: Wind accelerates moisture evaporation from exposed skin, which cools the surface temperature and enhances the chilling effect.
Conduction: Direct heat transfer from your body to cooler air. While less significant than convection, it contributes to overall heat loss in windy conditions.
Wind Speed: Higher wind speeds increase heat loss, but the effect diminishes at very high speeds. Wind speeds above 45 mph have minimal additional chilling effect.
Humidity: Moist air conducts heat away from the body more efficiently than dry air, making humid cold conditions feel even colder.
Activity Level: Physical activity generates body heat and can offset some wind chill effects, but exposed skin remains vulnerable.
Clothing: Wind-resistant outer layers significantly reduce wind chill effects by preventing air movement against the skin.
Frostnip (Mild Frostbite):
Frostbite:
Hypothermia:
Layering System:
Extremities Protection:
Activity-Specific Gear: Different activities require specialized equipment. Skiing, hiking, and construction work each have specific clothing requirements for cold weather safety.