A "blue norther" will lead to huge temperature drops this weekend. But what does the "blue" part mean, anyway?

The term "blue norther" is a phrase familiar mainly to native Texans.

Since trees and shrubs can live for hundreds of years, identifying these blue rings allows us to spot cold summers in the past. By looking at pine trees and juniper shrubs from northern Norway ...

Additionally, a blast of frigid Arctic air continues to sweep other areas of the country, with extreme cold warnings effecting millions of people in the Northern ... Dark blue means an extreme ...