Extreme cold in the south was predicted from global warming. How? Increased temperatures at higher latitudes leads to instability in the jet stream, a current of air which circles the north & keeps the super-cold (polar vortex) contained.

That instability let's the polar vortex slip around more. Sometimes here, sometimes there. Another effect is how hot it is in the Arctic right now.

And yes, this sort of thing will be more common in the coming years than we had been used to.

This is climate change.

The consequences for us, once we've gotten through this emergency? People further south will need to build their homes and other structures with more insulation.

They already should have, because it keeps out the summer heat too, but now freeze damage is on the radar.

The consequences for every other living thing? Lots of creatures and plants are experiencing deeper cold than they have in a very long time. The amount of death going on will take years of study to quantitate.

Species that were extending their range north in recent years will experience a dramatic reset further south.

Species with very limited ranges and numbers may go extinct.

Some forests will be full of winter kill for a few years. Other forests will prosper because their pests were killed off.

The primary effects will be hard to predict, though wildlife experts will be able to for their subject species. The secondary effects will be harder.

Broadly speaking, generalist species do better when ecological disruption increases. At the same time, specialist species do poorer.

Humans are very good at ecological disruption.