It has been my observation that here in the Chicago area rain occurs more frequently on Saturday and Sunday than on weekdays. Can you comment on why this is so?
Your question comes up occasionally, but the answer is that precipitation (rain or snow) does not fall more frequently on Saturday or Sunday than on other days of the week. The atmosphere does not operate on the “work-week” cycle, even though most of us do. We tend to notice rain (or snow) more often on weekends because those are the times when we are more attuned to the weather, but that doesn’t mean precipitation falls more frequently then.
A tabulation of wet and dry days shows that precipitation in Chicago occurs on either 33 or 34 percent of any day of the week, Saturdays and Sundays included.