Up until last week the most recent violent tornado in the United States during the month of August was the Windsor-Agawam F4 tornado on October 3, 1979. The tornado outbreak in Nebraska and Iowa on October 4th, 2013 produced an EF-4 tornado near Wayne, NE – the first “violent” October tornado in the U.S. in 34 years.
Violent tornadoes in October are rare. In fact, only 6 have been recorded in the U.S. since 1950. U.S. Tornadoes has a great page on violent tornado climatology and you can see in this graph just how unusual October violent tornadoes are compared to other months.
This year, the Windsor Locks F-4 tornado was bumped to 11th on the list of costliest tornadoes to strike the U.S. ($800+ million in damage in today’s dollars) and on Friday it lost the distinction as being the most recent violent tornado to strike the U.S. during the month of October.
The dearth of violent tornadoes in October nationwide is another reason why the ’79 Windsor Locks tornado was such a weird and freak occurrence.