There are three feline modern constellations: Leo, Leo Minor, and Lynx. They’re adjacent, so they’re all visible around the same time.
Leo’s heliacal rising from mid-northern latitudes is around early September. Alternatively, it is most easily visible in the evening in early May. So either early May or early September could be considered the “cat days”!
Sounds just like the sounds newer trucks make when they back up: https://m.youtube.com/watch?v=A3Wt1_51EVA