Cold weather in winter is often referred to as "Arctic air." Have you ever thought about what qualities air must have to be considered "Arctic?"
It turns out, there is no official temperature qualification. Instead, the only rule is that Arctic air must have come from the Arctic, or from north of the Arctic Circle where the sun does not rise during fall and winter.
Journalists and meteorologists alike often blur this distinction and will too often refer to any cold air as Arctic. In our region, there is a natural tendency to refer to any air that brings temperatures colder than zero degrees Fahrenheit as Arctic, and this is often correct, but not always.
For the record, the air coming our way tomorrow and into the weekend did, in fact, originate north of the Arctic Circle and north of Hudson Bay, so it is correct to refer to it as Arctic air.