Polar vortex explained: What is it and what does it mean for our winter weather in Ontario
Kidd explains the polar vortex is a large area of cold air and low pressure that lives over the North Pole, weakening in the summer and strengthening in the winter. In the winter, the polar vortex will expand in the Northern Hemisphere, sending cold air southward with the jet stream, according to the National Oceanic and Atmospheric Administration.