April 11
- 1965 – The peak of the 1965 Palm Sunday tornado outbreak brought numerous strong to violent tornadoes to the Upper Midwest and Great Lakes region in one of the most intense tornado outbreaks on record, resulting in 260 deaths and more than 3,400 injuries. With 18 tornadoes rated F4, this event is surpassed only by the 1974 Super Outbreak in the number of violent (F4/EF4 and F5/EF5) tornadoes.