(In honor of giving me a character idea, I follow your point! For today only.)
It was a grey, gloomy day for running a bookshop. If people weren't out on the streets, they usually didn't come in the front door. But if people were out in the streets and wanted to duck into the shop for a few... Well, if a downpour started then, there was always a decent chance of them picking up a book or three.
Word was that bad things were happening in town again. Hopefully they'd just pass one old bookseller by, without impacting the number of sales.