Meteorological Synopsis
The tornadoes occurred in a 450 miles (720 km) swath west-to-east from Clinton County, Iowa, to Cuyahoga County, Ohio, and a 200 miles (320 km) swath north-to-south from Kent County, Michigan, to Montgomery County, Indiana. The outbreak lasted 11 hours and is among the most intense outbreaks — in terms of number, strength, width, path, and length of tornadoes — ever recorded, including 4 "double/twin funnel" tornadoes.
This is the fourth deadliest day for tornadoes on record, trailing the Super Outbreak of April 3, 1974, which killed 315, the April 25–28, 2011 tornado outbreak which killed 322, and the outbreak that included the Tri-State Tornado which killed 747. It occurred on Palm Sunday, an important day in the Christian religion, and many people were attending services at church, one possible reason why some warnings were not received. There had been a short winter that year, and as the day progressed, the temperature rose to 83 °F (28 °C) in some areas of Midwestern United States.
Read more about this topic: 1965 Palm Sunday Tornado Outbreak