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Used in US and Canada for temperatures at or below 50°F (10°C) and wind speeds above 3 mph. Based on heat transfer from exposed face in wind.
WC (°F) = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T×V^0.16 (T=°F, V=mph)For metric inputs, convert or use the equivalent formula with °C and km/h. Wind chill is defined for bare skin — clothing and activity reduce effective exposure.
WC (°C) ≈ 13.12 + 0.6215T − 11.37V^0.16 + 0.3965T×V^0.16 (T=°C, V=km/h)Frostbite risk increases as wind chill drops below −18°C (0°F). Exposed skin can freeze in 30 minutes at −28°C wind chill; under 10 minutes below −40°C wind chill.
Frostbite time ∝ 1 / (|Wind chill − Skin temp|)Updated: July 2026
Wind chill ≈ 6°F (−14°C). Dress for mid-teens effective temperature: base layer, insulating mid-layer, windproof shell. Cover ears and fingers — frostbite risk in 30+ min exposure.
Wind chill ≈ −12°F (−24°C). Frostbite on exposed skin within 30 minutes. Full face protection, mittens, and limit exposed stops above treeline.
Effective wind speed combines headwind and riding speed. At 25 mph bike speed in 35°F air: wind chill ≈ 22°F. Windproof gloves and shoe covers essential.
At 10 mph, 30°F feels like 21°F. On summits and ridges, use forecast wind speed at elevation, not valley temperature. Add windproof layers when wind chill drops below 20°F.
Activity heat masks wind chill while moving. During stops, wet base layers and lost metabolic heat cause rapid core cooling. Add insulation immediately when stopping above treeline.
Wind chill describes how cold exposed skin feels when wind strips away the insulating layer of warm air. It does not change actual air temperature but increases heat loss and frostbite risk. This calculator uses the North American and UK wind chill formulas for outdoor activity planning.