September 21
- 1894 – A major tornado outbreak resulted in at least 63 deaths across Iowa and Minnesota. An F4 tornado or tornado family leveled farms in Kossuth, Hancock, Cerro Gordo, and Worth Counties, Iowa, killing 25 people. Another F4 tornado or family tracked from near Mason City, Iowa through Le Roy, and Spring Valley, Minnesota, killing 16 more. Another tornado family, with members of to F5 intensity moved from near Whittemore, Iowa to near Kiester, Minnesota, killing at least 14 people. Five farms in Kossuth county were destroyed with little trace left behind.
- 1924 – A major tornado outbreak killed 34 people in Wisconsin. A tornado or tornado family of at least F4 (probably F5) intensity killed 18 people in Taylor and Clark Counties. Farms were completely obliterated near Rib Lake. An F4 tornado killed seven people near Sanborn, including five in one home.