Customers won't step out of their car, if they don't believe you are open
I am often amazed at how much effort retail stores or restaurants put into the overall look and design of their building or space - but how little effort on making it clear to prospective customers that they are open.
A translucent 4"x6" square with the weekly hours is not going to entice someone out of the car. During summer in Oklahoma, the temperature can be 100 degrees or higher: no one is going to get out of his or her car's air conditioning to check the door of a store.