Y: New York is just one of those places where when it’s cold… it’s COLD cold. But in New York, we don’t say it’s cold outside, we say it’s brick outside.
This is definitely one of those slang terms that is practically branded by the region that uses it. It’s possible that the reason New Yorkers use the word “brick” to refer to the drops in temperature is that it’s extremely telling of what city it’s from. During the development of New York, and up to this day, the vast majority of the buildings were made out of brick. If you’ve ever touched the side of a brick house during the winter months, you’d know that the material absorbs the surrounding temperature. In fact, however cold it is outside, bricks usually feel ten times colder. However, the further you get from the general city area, the more buildings you’ll see made out of brick. That being said, it’s possible that this slang term is generally used by New Yorkers who live in a more suburban area like the Bronx or Queens, for example.