 However, most Blue Northers don't advance as far south as Mexico, and even the most severe examples typically reach their apex midway through Texas.For example, cities in North Texas, like Dallas, experience drastically more Blue Northers than cities along the Gulf of Mexico, like Houston.As a city is struck by a Blue Norther, its temperatures can be 30 to 50 degrees colder than neighboring cities that are only a few miles away that have not yet been struck.