Wind chill calculator
Wind strips heat from exposed skin. The wind-chill index estimates how cold it feels on bare skin, using the formula adopted by Canadian and US weather services in 2001. It applies to temperatures at or below 10°C and wind above about 5 km/h.
What to do with the number
Below about −28°C wind chill, keep exposed skin to a minimum: face covering, goggles or glasses, insulated mittens rather than gloves. Below −40°C, limit time outdoors and travel with someone who can watch your face for the white patches of early frostbite.