Hats, coats and gloves are recommended. 1400 - 1600 Outdoor work and travel are safe with quality winter clothing. 1600 - 1800 Frostbite can occur with prolonged exposure. Heavy outer clothing is essential. Your weather office will add the current wind chill to the public forecasts at this level.
Frostbite can occur in a few minutes.
Multiple layers of clothing become essential. 2000 or more Unprotected skin can freeze in one minute. Adequate face protection becomes important. Elementary school children require continuous adult supervision while outdoors. Work and travel alone is not advisable.