A Texas Norther, also known as a blue norther, is a cold front in the U.S. state of Texas, marked by a sudden drop in temperature (sometimes up to 25 degrees F within one hour), heavy precipitation, and dark blue skies moving across the state. The phrase originated within Texas, where the land is very flat, perhaps making the approaching front seem darker and more threatening. Even so, there is nothing special about a Texas Norther; in fact, most people do not realize that other states also experience these types of cold fronts; however they are usually not named after the state. The cold front usually originates far north of the state, hence the "norther," causing cool temperatures and precipitation.
Because Texas lies to the west of a major body of water and to the lee of the Rocky Mountains in the zone of the westerlies during the winter, temperatures closely follow the sun, and temperatures that precede a Texas norther can, but very rarely, reach 85°F in January and 90°F under bright sunlight in nearly-calm conditions even as far north as Dallas before the cold front passes through. Winds turn sharply to a northerly direction and become very strong. Windchill due to a combination of cold temperatures and strong winds is dangerous to anyone who is caught unaware and