As Toronto remains under an extreme cold weather alert, the term "wind chill" will likely send shivers down your back. But what does it really mean?
Formally called the "wind chill equivalent temperature," it's a value that shows how the wind combined with the cold will affect your body.
"We measure the wind and we measure the temperature and we plug them into a mathematical model to get the wind chill equivalent temperature," arctic physicist Randall Osczevski, who helped developed the system, told CTV Toronto.
He explains the wind can cut through a natural atmospheric insulation around a person's body, putting it at risk of cold-related health problems.
"It can produce hypothermia and frost bite," Osczevski said.
Weather forecasters say temperatures without considering the wind chill can often trick people into believing that it is warmer outside.
"It can be very tricky when you're inside looking outside because you can’t see wind and you almost fool yourself into thinking it's not that cold, so you don't dress for it," CTV Toronto's Tom Brown said.
Experts say on frigid cold days when the wind chill pushes the mercury even lower, people should be concerned about exposed skin and the tips of their fingers, toes, ears and nose.
"When we're out in cold weather like this and you’re feeling a little bit of pain in your ears, or pain in your fingers or toes, the nerve receptors that sense pain are the same ones that sense cold," said Greg Wells, a University of Toronto kinesiology professor.
Under cold conditions, experts say blood is drawn away from a person's hands and feet, and carried to the organs. A person then begins to shiver as a method to stay warm.
"That's designed to generate heat," Wells said.
He adds that shivering is also a warning sign that it may be time to go indoors.
"It's a really good sign that you need to get in and get warm."
With a report from CTV Toronto's Collin D'Mello
