September marked the end of the warm season for the United States and the tornado activity continued its annual decline. According to preliminary data from the Storm Prediction Center, during September there were 62 preliminary tornado reports across the country, which was slightly below average. The majority of the tornadoes reported during the month occurred along the path of tropical storm Lee. The tropical system quickly became extra-tropical after making landfall in Louisiana on September 3rd. The system interacted with a frontal system moving across the country, spawning severe weather from Louisiana into the Northeast. There were no reported tornado fatalities during September.
NOAA's National Centers for Environmental Information