How cold is the cold wave in America?

It seems that this cold wave is not too cold ... the lowest is MINUS 30 or 40 degrees. ...

The problem is that if there is cold air heading south in Ma Pingchuan, the central plain of the United States, it will go all the way down to the south coast, and a large area will be affected. That's why there are such serious consequences.

This shows the importance of mountains in the north. ...