The 1955 Great Plains tornado outbreak was a deadly tornado outbreak that struck the southern and central U.S Great Plains States on May 25–26, 1955. It produced at least 46 tornadoes across seven states including two F5 tornadoes in Blackwell, Oklahoma, and Udall, Kansas that caused most of the casualties. The outbreak killed 102 from three tornadoes while injuring hundreds more. Unusual electromagnetic activity was observed, including St. Elmo's fire.