Most tornadoes in the United States occur east of the Rocky Mountains. The Great Plains, the Midwest, the Mississippi Valley and the southern United States are all areas that are vulnerable to tornadoes. During the winter months of the year, tornadoes have been known to hit the Southern United States and Southeastern United States the most, but have hit other areas as well. [ 8 ] One notable recent example of a winter tornado outbreak was the 2008 Super Tuesday tornado outbreak on February 5 and February 6, 2008. 84 tornadoes occurred over the course of the outbreak.