Powerful winter storm hits eastern half of the US

Winter storms are bringing severe weather to several parts of the US this weekend — including the kind of brutal cold that can cause frostbite.

Frostbite happens when the skin and the tissue under the skin freezes, which can happen much more quickly than you might imagine. It can cause blood clots, gangrene, and long-lasting damage to muscles, tendons, nerves and bones.

The cause: Frostbite is affected by both the outside temperature and the wind chill factor. As the speed of the wind increases, our bodies cool at a faster rate, causing the skin temperature to drop. Higher altitudes can also increase the speed at which skin can freeze.

The National Weather Service has created a wind chill chart that shows the time it might take to develop frostbite at varying temperatures and wind speed. It shows that your skin would freeze in a scant five minutes if you were out in minus 25 degrees Fahrenheit (minus 31.7 degrees Celsius) with a wind speed of just over 25 miles per hour.

Risk factors: You are more susceptible to frostbite if you smoke, take medications called beta-blockers, have poor blood supply to the legs, or have diabetes or Raynaud syndrome, a condition in which strong emotions or cold temperatures cause blood vessels to spasm and block blood flow to extremities.

Older people and people who live outside without proper clothing, heating and food are also at high risk, as are hikers and hunters who aren’t properly clothed and stay outdoors too long.

Here’s more on how to avoid frostbite.