Winter Vortex 2025. The polar vortex is an area of low pressure that exists over the arctic at the upper levels of the atmosphere, in the stratosphere, during wintertime. What is the polar vortex?
Winters with at least one polar vortex disruption/sudden stratospheric warming (ssw) are marked with a black outline (and years with two have two circles). Looking below at the forecast for late september, you can see the polar vortex is already.