Sudden loss of body heat and frozen extremities become serious possibilities with temperatures near zero and below.
With local temperatures predicted to be as low as minus 10 degrees overnight Tuesday, experts remind you to dress warmly and avoid over-exertion if you plan to be outdoors for any extended period.
"If you become too active, you'll sweat -- and you don't want that when it's so cold," said Dr. John Torres of Premier Urgent Care. "You also have to worry about breathing cold air. Our bodies compensate for that to a certain extent. If you breathe cold air and feel discomfort, get inside to a warm area."
Torres said children and the elderly are especially vulnerable to such cold weather.
KRDO Newschannel 13 spoke with several people who routinely work outside all day, regardless of weather.
"I've worried about frostbite before," said Steven Trujilo, a sign installer and repairman. "My fingers and toes got real bad and started to hurt."
"I like to try and stay moving and make sure I have good winter wear," said Nicholas Tisdel, a sanitation worker. "Between those two, it keeps me pretty warm."