Tornado climatology
The United States averaged 1,274 tornadoes per year in the last decade. April 2011 saw the most tornadoes ever recorded for any month in the US National Weather Service's history, 875; the previous record was 542 in one month. It has more tornadoes yearly than any other country and reports more violent (F4 and F5) tornadoes than anywhere else.
Tornado climatology
A large region of South America is characterized by storms that reach the level of supercells and produce intense hailstorms, floods, and tornadoes during the spring, summer, and early fall. The region recently appointed as the (South America) is considered as the second largest in the world in terms of the formation of extreme weather events. It covers most of central Argentina, southern Paraguay, southeastern Brazil, and Uruguay.