I live in La Grange and it seems that my area often receives much less precipitation than other Chicagoland locations. Why should this be?
Richard Stillabrett, La Grange
There is no climatic evidence to suggest that specific locations or areas of Chicagoland receive less (or more) precipitation than others. The exception is that certain specific weather phenomena (such as lake-effect snow) do favor specific areas. With those exceptions aside, all locations in Chicagoland receive equal precipitation. Given sufficient time, perhaps decades, it all evens out.
Noticeable precipitation differences over short distances are usually related to differences in elevation between the locations, but that is not a factor in the Chicago area. The region is flat enough to eliminate elevation differences to account for precipitation differences.
That being said, metropolitan Chicago covers a huge area. It includes portions of northwest Indiana and southeast Wisconsin and areas to the northwest, west, southwest and south of Chicago. Precipitation tends to be greater to the south of Chicago and lighter to the north. This is part of the varying precipitation regime across the Midwest.