When I think of Setting, I know I have to think about time. Time can be a valuable and vital part of setting the story. I seldom write historical romances but I do know when I have the time period of the story is a vital part of establishing the validity of the story. Life and attitudes were different in pre-written times and also in each century of man's existence. So making sure to read a bit about the time I'm writing about is important. Thinking about books I've written with a medical background, during the years I've been writing many things have changed, especially in the medical field so the time I'm writing about plays an important.
Time also involves seasons of the year. Each season and each month has a different flavor. Knowing this is important to the writer. One could have a snow storm in May but much would depend on where the story takes place. I do remember once when it snowed on Memorial Day and that was because of a freak cold front. Would I use this in a story. Maybe but probably not. So knowing the season it important. Also the month of the year. Though spring covers a number of months usually three, July is different from August. The writer needs to be aware of these things.
Time also involved time of day. Knowing when the sun rises might effect a story. Knowing when the sun sets could also have an effect. Having the villain creep in during the dark hours of the night would be different that having him creep about during the day.
So when you're writing be aware of time and the story will seem more real to the reader.