Polar Vortex In Chicago 2025 Forecast. On tuesday, after the first significant winter storm of the year blasted a huge swath of the country with ice,. When the polar vortex gets weaker, or breaks up, it unleashes cold air to the south.

A weaker polar vortex usually means a weaker jet stream, which increases the chance of a more dynamic. Early data shows that the polar vortex is likely to be weaker than normal in the winter of 2024/2025.