During autumn, the atmosphere transitions from the warm and humid air of summer to the cold and dry winter. This creates a more active jet stream and an increase in thunderstorms. Indiana usually experiences a few rounds of severe weather during the fall, and some of these storms produce tornadoes.
Below is a graph of the average number of tornadoes per month in Indiana during the period 1981-2010:
Notice the secondary maximum during the fall months. Next is a plot of tornadoes by time of year for the entire U.S. Again you can see a secondary maximum during the fall months:
Take time now to review your safety plans to prepare for the fall severe weather potential. Additional information is available on our Preparedness page.
Notable Indiana Tornado Events during fall (September-November):