The cold front originates from the north, hence the "norther", and can send temperatures plummeting by 20 or 30 degrees in merely minutes.
The Midwestern United States lacks natural geographic barriers to protect itself from the frigid winter air masses that originate in Canada and the arctic.
Multiple times per year conditions will become favorable to push severe cold fronts as far south as Texas, bringing sleet and snow and causing the windchill to plunge into the teens.
Depending on the time of year, high temperatures that immediately precede a Texas Norther can reach 85 °F (29°C) or even 90 °F (32°C) under bright sunlight in nearly-calm conditions before the cold front approaches.
However, most Blue Northers do not advance as far south as Mexico, and even the most severe examples typically reach their apex midway through Texas.