The Cat Who Dropped a Bombshell by Lilian Jackson Braun

While the town of Pickax is swept up in its sesquicentennial celebrations, Koko has developed a strange new hobby: He drops himself from balconies, occasionally landing in the oddest of places. When a young man comes to visit his wealthy relatives, Koko plummets straight onto his head! Meanwhile, a hurricane is brewing, and the visitor's family members soon fall deathly ill. Qwill has his work cut out for him as Pickax-as foreshadowed by Koko-is about to be hit by a bombshell.