On April 30, 1936, a large, destructive tornado formed in far northeast O'Brien County, moved across northwest Clay County, and into southwest Dickinson County. The tornado continued until it lifted on the south end of West Okoboji. It is, as of today, the only known deadly tornado in Dickinson County. The tornado killed two people, one in Dickinson County and the other in Clay County; and at least 13 were injured. A book called Significant Tornadoes 1880-1989 by Thomas P. Grazulis rates this tornado as an F4, using the original Fujita scale. This would suggest winds were from 207 to 260 mph and strongly built homes have all interior and exterior walls blown apart; cars thrown 300 yards or more in the air. Given the descriptions of the damage from this tornado, and the few pictures that exist today, a rating of this magnitude may not be out of the question.