Accuracy of electronic temperature display

[alienmagic]

I have a 97 Jimmy SLT. How accurate is the electronic temperature displayed on the overhead console supposed to be? Mine is usually anywhere from 2 to 4 degrees higher than the actual outdoor temperature (according to the digital temperature displays of banks/businesses I drive by, as well as local radio announcements). It's pretty close, so it's no big deal to me, but should it be more accurate than that?