Here in Middle Tennessee . We get tornadoes every year . Very often in the spring or fall when the weather is changing . But in July and August ( dog days of summer ) it's very hot and the air is still and calm . A tornadoe can happen without warning .
Take a look at the area around OKC where I grew up. Just go from the Tip of Texas southern most point, one finger length due north, in the middle of all the pink lines there.