NASHVILLE, Tenn. (WKRN) — The state of Tennessee is no stranger to tornadoes, and on average, about 30 touch down each year. You probably know that spring is peak tornado season in the mid-state, but did you know that September is the month when tornadoes are least likely?

The National Weather Service in Nashville records every tornado that impacts Tennessee, and has tornado data going all the way back to 1811. From 1811 to 2025, only 12 tornadoes have been recorded during September.

This may seem to be both too low and incorrect because months like April and May have hundreds of tornadoes, but tornadoes are extremely rare in September.

It all has to do with the ingredients needed for a tornado to form. Tornadoes need three things:

• Storm fuel is the amount of moisture or humidity in the air. When it is really hot and humid, there is plenty of fuel for thunderstorms.
• Wind shear is the wind speeds at all levels of the atmosphere. This means tornadoes are most likely when the winds are strong from the surface all the way up to the jet stream.
• Lifting mechanisms are areas of low pressure and cold fronts. In order to get all of that storm fuel up in the atmosphere, there needs to be something that lifts it up. Areas of low pressure and especially cold fronts do that.

Each season has some of these ingredients, but some seasons are missing one or two of them.

For example in winter, there is typically a lot of wind shear and lifting mechanisms, but not enough storm fuel.

Spring, on the other hand, is when we typically see the most time when all three of these ingredients are present. This is why the spring is tornado season in Tennessee.

During the summer, we typically have tons of storm fuel, but no wind shear or lifting mechanisms. This is why we see thunderstorms almost every day, but they rarely produce tornadoes.

In the fall, especially during early fall, all three of these ingredients are typically missing. Tornadoes do become a little more likely in November.

One exception is when the remnants of tropical systems move over Tennessee. The remnants of those tropical systems can bring more storm fuel and wind shear and could produce tornadoes. The tornadoes produced by a tropical system are usually weak and short-lived.

Enjoy the quietest time of the year for twisters!

News Source : https://www.wkrn.com/news/sept-tornadoes-least-likely-why/