This is how we end up with extreme weather like what we saw in Florida this year which had never happened before.
Extreme cold snaps
Climate change affects the jet stream because different parts of the planet are warming at different rates. In particular, the Arctic is warming fastest. This means that, as the Earth warms, the temperature difference between the Arctic and mid-latitudes is getting smaller.
This makes the polar jet stream slower and weaker. That slower jet stream has less eastward momentum and is more likely to bend north and south as it encounters small variations in temperature and pressure.
If it bends far enough, the barrier between Arctic and mid-latitude air can plunge as far south as Mexico, bringing Arctic temperatures with it. These wavy jet streams span the Earth, so strange weather may be seen all around the northern hemisphere, with unusually warm temperatures in parts of the Arctic at the same time extreme cold spells reach far south. In February 2021, for instance, Texas endured over a week of freezing temperatures the state was not prepared for, causing power outages and killing hundreds, while much of northern Eurasia also saw extreme cold. And because a weak jet stream moves slowly, these weather conditions can last for days at a stretch.
Source:
https://climate.mit.edu/explainers/p...d-polar-vortex