This photo shows a residential neighbourhood on 25 January 2026 in Columbia, Missouri - Photo credit: GettyWhat is the polar vortex, and why does it matter? These winds normally form a tight barrier that keeps the coldest Arctic air locked near the North Pole. The polar vortex is often confused with the polar jet stream, but they sit in completely different layers of the atmosphere. When the Arctic polar vortex is especially strong and stable (left globe), it encourages the polar jet stream, down in the troposphere, to shift northward. These are persistent high-pressure systems that can stall weather patterns and make the jet stream more distorted.