If the hero is filled with rage and about to rearrange the villain’s face for slashing all the tires on his car, a writer might be tempted to set the scene at night, on a deserted street with the air so cold it bites. What if instead the hero confronts the villain at the county fair on a bright blue day, with carousel music and popcorn smells and squealing kids bouncing the balloons tethered to their wrists? Think about how that level of rage stands out against such a happy, family-oriented Setting.
In your own life, how often does bad news come on a gloomy, rain filled day? Does it wait until you have time for it, or for you to be in the mood to receive it? No. Setting is an opportunity to create a contrast that forces the reader to pay attention to the emotions at work and understand their depth.