You don’t look at the wind chill
Any time your skin is exposed to temperatures below freezing, you’re at risk for frostbite. That risk increases when you factor in wind chill, which tracks how cold you actually feel thanks to cold winds. As the wind gets stronger and colder, your body loses heat faster and skin temperature drops. When the air temperature is 0˚F, for example, and the wind blows at 15 mph, the wind chill is -19˚F. All it takes is 30 minutes for frostbite to kick in if your skin is exposed to this temperature. (This chart from the National Weather Service explains how long it takes to get frostbite based on a given temperature and wind speed.)
You drink before heading out in the cold
Heading to happy hour? You might be putting yourself at risk of frostbite. Why? One of your body’s natural responses to cold weather is to constrict blood vessels, but alcohol can dilate them. This causes your body to lose heat faster, which can make your skin freeze quicker.